Moodle in English: Error: Database Connection Failed

Error: Database Connection Failed

by Patrick Masson - Monday, December 14, 2020, 7:41 AM

I am getting three error messages--at various times--on a new installation of Moodle 3.10 (Build Date: Dec 9 2020 02:53:22 ) apparently related to database connectivity (see below):

1. "Error: Database connection failed" intermittent interruptions as users (all user types, admin, faculty, student) navigate the site (after clicking a link). Refreshing/reloading the page immediately resolves the issue, with the page loading normally. Regular use continues as expected, until, after some time/activity, the error interrupts use again.

Error message.

2. "Could not connect to server." This warning notice appears on a web page as users are editing a page.

3. A pop-up notice appears stating, "dbconnectionfails" (no screenshot provided). This pop-up can be closed and users can continue on normally.

Server details:

Moodle 3.10:
CentOS 6.10
Apache 2.4.46
PHP 7.2.34
MySQL 5.7.32
Operating System Linux/CentOS
Hosting via Bluehost VPS

Moodle server check

Looking at, "Dashboard" -> "Site administration" -> "Server" -> "Environment" reveals server checks = "Status OK".

config.php

The config.php is based on the included template with all parameters defined correctly. The database is running and accessible, with only the above periodic notices indicating an issue.

MySQL log

I checked today's (2020-12-13) MySQL error logs (/var/lib/mysql/HOSTNAME.err) and found:


     2020-12-13T00:30:01.590956Z 20681 [Note] Got an error reading communication packets
     2020-12-13T02:49:32.508568Z 21047 [Warning] Host name 'zg-0915b-92.stretchoid.com' could not be resolved: 
     Name or service not known
     2020-12-13T03:36:07.858565Z 21162 [Note] Got an error reading communication packets
     2020-12-13T04:30:02.004580Z 21298 [Note] Got an error reading communication packets
     2020-12-13T07:06:08.691620Z 21680 [Warning] IP address '89.248.169.12' could not be resolved: 
     Temporary failure in name resolution
     2020-12-13T07:40:11.441514Z 21766 [Note] Got an error reading communication packets
     2020-12-13T08:30:01.641797Z 21892 [Note] Got an error reading communication packets
     2020-12-13T09:25:35.334688Z 22029 [Warning] IP address '139.59.59.68' could not be resolved: 
     Name or service not known
     2020-12-13T09:25:45.478482Z 22030 [Warning] IP address '190.144.55.6' could not be resolved: 
     Name or service not known
     2020-12-13T11:40:59.907882Z 22359 [Note] Got an error reading communication packets
     2020-12-13T12:30:02.066380Z 22476 [Note] Got an error reading communication packets
     2020-12-13T13:53:07.812379Z 22682 [Warning] IP address '188.166.125.36' could not be resolved: 
     Name or service not known
     2020-12-13T15:10:08.271476Z 22878 [Warning] IP address '83.97.20.31' has been resolved 
     to the host name '31.20.97.83.ro.ovo.sc', which resembles IPv4-address itself.
     2020-12-13T15:42:13.853217Z 22953 [Note] Got an error reading communication packets
     2020-12-13T16:03:41.688753Z 23092 [Warning] Host name '107-175-61-178-host.colocrossing.com' 
     could not be resolved: Name or service not known
     2020-12-13T16:30:01.160697Z 23301 [Note] Got an error reading communication packets
     2020-12-13T16:37:21.232994Z 23351 [Warning] Hostname 'rederatural.com' does not resolve to '104.140.188.2'.
     2020-12-13T16:37:21.233275Z 23351 [Note] Hostname 'rederatural.com' has the following IP addresses:
     2020-12-13T16:37:21.233288Z 23351 [Note]  - 23.82.12.32
     2020-12-13T19:43:40.917874Z 23855 [Note] Got an error reading communication packets
     2020-12-13T20:30:01.352053Z 24058 [Note] Got an error reading communication packets

RTFM

I did try to research and resolve the issue myself:

MoodleDocs: Main page ► Managing a Moodle site ► Errors FAQ

Error: database connection failed
- Suggestion, "Your database server isn't installed or running."
  - Not relevant: database is running as error only occurs intermittently
- Suggestion, "If you are attempting to run two instances of Moodle on different ports..,"
  - Not relevant: only running one instance.
- Suggestion, "You don't have the PHP mysql or postgresql extensions installed..."
  - Not relevant, per above server checks, Moodle admin panel reports, "Status OK" with all PHP extensions installed.
- Suggestion, "You haven't created a Moodle database and assigned a user with the correct privileges to access it."
  - Not relevant, as the database is accessible and running with only intermittent errors reporting.
- Suggestion, "The Moodle database settings are incorrect..."
  - Possible. The file config.php was created from the template file config-dist.php provided with the installation. While the connection to the database must be defined properly (as the database is accessible with only intermittent errors), other critical settings may not be defined appropriately. I do not know what those settings might be.
- Suggestion, "Check that there are no apostrophes or non-alphabetic letters in your MySQL username or password."
  - Not relevant, again the error message is only occurring intermittently, so the issues related to access (path, db name, user, password) are not the issue.
- Suggestion, "You are using MySQL version 4.1 or higher but the PHP MySQL extension is pre-4.1..."
  - Not relevant, as errors are intermittent. The expectation would be that any access/config errors would affect all access to MySQL, not just occasional access. Also, as this is a new install, I would not expect any conflicts with extensions pre PHP Version 7.4.13 (the only version used with this installation).
- You are using Fedora core 3 or some other Linux system with SELinux installed and enabled.
  - Not relevant, running "sestatus" reveals: "SELinux status: disabled"
- Suggested, "Mac OSX users..."
  - Not relevant, running CentOS.

Moodle in English Forums: Hardware & Performance

Moodle forum posts, including:

MoodleDocs, Main page ► Managing a Moodle site

Performance and Performance FAQ

Any suggestions very much appreciated.

Thanks,
Patrick

Re: Error: Database Connection Failed

by Ken Task - Monday, December 14, 2020, 9:27 AM

Good job sharing info and providing info ... but ... should focus on DB.

"Got an error reading communication packets"

Networking does come before application ... application here is code making queries of DB @DB server.

https://www.percona.com/blog/2016/05/16/mysql-got-an-error-reading-communication-packet-errors/

Offers a conclusion:
Conclusion:
"In addition to diagnosing communication failure errors, you also need to take into account faulty ethernets, hubs, switches, cables, and so forth which can cause this issue as well. You must replace the hardware itself to properly diagnose these issues."

and
https://dzone.com/articles/mysql-got-an-error-reading-communication-packet-er

refers to Percona!

Since you can't do what Percona suggest in replacing hardware/networking etc, the issues might need to involve provider (where you host).

However, before you do that ...

Bluehost VPS - is it managed or unmanaged?

Is this a standalone server where the DB server is on the same machine?
That question relates to .err log for DB server and seeing multiple machines
attempting access to DB server. Also relates to config.php file and where DB server is hosted.

If DB server on same as code, in config.php DB server should be localhost.
A localhost uses socket connections by default and not TCP/IP stack.

In DB server config of MySQL ... what is DB host?

DB server has a DB that controls users and clients that can connect to it.
That should allow only localhost and no others.

Since allowing only localhost, one could 'skip_networking' ... no need to do a DNS lookup on every attempted connection. localhost should always resolve to loopback 127.0.0.1 in IPv4 and that reference should be in /etc/host file.

Suggest installing MySQL Tuner (a perl script) and run it as superuser of DB server. See what it recommends.

https://github.com/major/MySQLTuner-perl

And don't forget to check out what your own provider might offer:

https://www.bluehost.com/help/article/vps-dedicated-site-performance

'SoS', Ken

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[SOLVED] Re: Error: Database Connection Failed

by Patrick Masson - Tuesday, December 15, 2020, 2:38 AM

Thanks Ken for taking the time to reply.

Your reminder, "If DB server on same as code, in config.php DB server should be localhost" was the key. The domain is "locusplex,us" and apparently when editing the config.php file I let autofill complete "$CFG->dbhost = 'loc...'" so I got locusplex.us instead of localhost and then just completed the URL out of habit. I must have looked at that 20 times and read right over it never noticing. Put this is the "Duh, sorry for wasting everyone's time" column.

Looks like the ol'saying, "Many eyeballs..." is still accurate. Thanks again,
Patrick

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Re: [SOLVED] Re: Error: Database Connection Failed

by Ken Task - Tuesday, December 15, 2020, 4:02 AM

Yep ... more eyes are better! Agreed!

But now to the biggy ... CentOS 6 has reached end of life ... no more updates for anything. Suggest you contact hosting provider to ask how to upgrade the entire OS to at least CentOS 7 (wouldn't go CentOS 8).

CentOS 6 doesn't have an 'upgrade in place' - well, should say nothing that is 100%.

With Rackspace servers, engineers there said to backup to a storage device, then wipe out 6 to install minimal 7, rebuild server. Once MySQL/PHP/Apache talking, then restore from site backups.

Even if your hosting provider says they can do ... think I'd make sure I had a site backup stored off server.

'SoS', Ken

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Re: [SOLVED] Re: Error: Database Connection Failed

by Patrick Masson - Tuesday, December 15, 2020, 4:07 AM

Yup, on it: https://my.bluehost.com/hosting/help/centos-cpanel-upgrades

Thanks again.

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Re: [SOLVED] Re: Error: Database Connection Failed

by Steve Zielinski - Sunday, December 20, 2020, 3:49 AM

You didn't waste anyone's time, as I am having the same issue. I have a dumb question. Why does this create an intermittent problem and not a consistent fail?
Steve

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Re: [SOLVED] Re: Error: Database Connection Failed

by Ken Task - Sunday, December 20, 2020, 5:40 AM

https://dev.mysql.com/doc/refman/5.6/en/host-cache.html

DNS servers could have settings so that clients making too many queries in a time frame are denied responses. That would slow down a moodle's performance and from time to time a 'fail', I would think.

Thus, if DB server on same as code, skip networking and in config of moodle localhost (not an FQDN). localhost uses a socket connection to DB ... no DNS query.

First link from a google search as suggested by Mr. V, rendered this:

https://nixcp.com/skip-name-resolve/

'SoS', Ken

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Re: Error: Database Connection Failed

by Ken Task - Monday, December 14, 2020, 9:44 AM

Biggy ... if you are sure it's CentOS 6 ...

EoL for CentOS 6 ... November 30, 2020 ... tis Dec. 2020

https://endoflife.software/operating-systems/linux/centos

'SoS', Ken

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Re: Error: Database Connection Failed

by Patrick Masson - Sunday, December 27, 2020, 6:34 AM

Hi Ken,

I just migrated from CentOS 6 to 7.

After the update, all services are working fine (NextCloud, MediaWiki, etc.), except...wait for it...Moodle. I now get:

Error
Error: Database connection failed
It is possible that the database is overloaded or otherwise not running properly.
The site administrator should also check that the database details have been correctly specified in config.php

After the server OS upgrade I restored all files from the backups taken just prior to the upgrade. Again all other services are working, leading me to believe the database, php, etc. are running properly. I also checked config.php to ensure it was correct, which I believe it is (again, this is the same file from before the update, so nothing was changed).

I did get this suggestion from my hosting provider...

I had a look in the issue and I see component.php on line 1114 in path /home/locusple/public_html/school/moodle/lib/classes is showing issue. Looks like some configuration has been effected due to upgrade done from your side . I would request you to either check with the file script or re upload the latest backup that you are having, that should help.

Looking at line 1114:

/**
     * Returns hash of all versions including core and all plugins.
     *
     * This is relatively slow and not fully cached, use with care!
     *
     * @return array as (string)plugintype_pluginname => (int)version
     */
[1114] public static function get_all_versions() : array {
        global $CFG;

        self::init();

        $versions = array();

        // Main version first.
        $versions['core'] = self::fetch_core_version();

        // The problem here is tha the component cache might be stable,
        // we want this to work also on frontpage without resetting the component cache.
        $usecache = false;
        if (CACHE_DISABLE_ALL or (defined('IGNORE_COMPONENT_CACHE') and IGNORE_COMPONENT_CACHE)) {
            $usecache = true;
        }

        // Now all plugins.
        $plugintypes = core_component::get_plugin_types();
        foreach ($plugintypes as $type => $typedir) {
            if ($usecache) {
                $plugs = core_component::get_plugin_list($type);
            } else {
                $plugs = self::fetch_plugins($type, $typedir);
            }
            foreach ($plugs as $plug => $fullplug) {
                $plugin = new stdClass();
                $plugin->version = null;
                $module = $plugin;
                include($fullplug.'/version.php');
                $versions[$type.'_'.$plug] = $plugin->version;
            }
        }

        return $versions;
    }

As suggested I re-uploaded the entire Moodle directory, but that did not resolve the issue.

I also restarted MySQL and changed the database password (this was suggested as a way to force a db reconnection, config.php was updated with the new password as well).

Any thoughts appreciated.

Thanks - Patrick

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Re: Error: Database Connection Failed

by Ken Task - Sunday, December 27, 2020, 7:27 AM

If you didn't know it before ... you do now ... moodle is a beast to itself and one cannot compare functioning WordPress, MediaWiki, nor any other open sourced AMP stack to Moodle ... period!

Moodle is more version sensitive.

So ... moodle version is (devils are always in the details)?

Erase contents of moodledata ... that's moodledata ... 'cache' and 'localcache'.

Did you run the environment check?

All AMP stack apps that have version requirements are more exacting than 'MariaDB 10.x'. So using:

http://www.syndrega.ch/blog/#php-and-dbms-compatibility-of-major-moodle-releases

Is your MariaDB version is as it should be?

Is the value for 'dbcollation' in config.php match the database, all the tables in the database, and all columns in those tables?

run code/admin/cli/mysql_collation.php script.

There are also 2 other DB scripts at location that might be worth checking.

'SoS', Ken

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Re: Error: Database Connection Failed

by Patrick Masson - Sunday, December 27, 2020, 8:41 AM

Thanks for the reply Ken!

> If you didn't know it before ... you do now ... moodle is a beast to itself and one cannot compare functioning WordPress, MediaWiki, nor any other open sourced AMP stack to Moodle ... period!

I'll take your word for it

> So ... moodle version is (devils are always in the details)?

Moodle 3.10
Apache 2.4.46
PHP 7.3.25
MySQL 5.7.32
Operating System Linux/CentOS 7
Hosting via Bluehost VPS

> Erase contents of moodledata ... that's moodledata ... 'cache' and 'localcache'.

I deleted all contents in moodledata, locally, /schoolMoodleData/cache/ and /schoolMoodleData/localcache'" including:

/schoolMoodleData/cache/
/schoolMoodleData/cache/cachestore_file/...
/schoolMoodleData/cache/filelocks/...
/schoolMoodleData/cache/core_component.php

/schoolMoodleData/localcache/core_admin/...
/schoolMoodleData/localcache/htmlpurifier/...
/schoolMoodleData/localcache/mustache/...
/schoolMoodleData/localcache/requirejs/...
/schoolMoodleData/localcache/theme/...
/schoolMoodleData/localcache/.lastpurged
/schoolMoodleData/localcache/0721c03c549edb67e8df439bd6fd02e059d5fa3e
etc.

> Did you run the environment check?

I do not believe I can run a check as https://locusplex.us/school/moodle/admin/environment.php is inaccessible (I get the same error message). Is there a way to run an environment check with the Moodle inaccessible?

> All AMP stack apps that have version requirements are more exacting than 'MariaDB 10.x'. So using: http://www.syndrega.ch/blog/#php-and-dbms-compatibility-of-major-moodle-releases Is your MariaDB version is as it should be?

Reviewing the webpage, I appear to be inline with the PHP and DBMS recommendations.

Suggested | Running:

Moodle 3.10 | Moodle 3.10
PHP min: 7.2.0 - max: 7.4 | PHP Version 7.3.25 (local domain/directory with Moodle set to PHP 7.3 (ea-php73))
MySQL min: 5.7 - max: 8.0 | MySQL Version 5.7.32

> Is the value for 'dbcollation' in config.php match the database, all the tables in the database, and all columns in those tables?

I believe so...

details of database

> run code/admin/cli/mysql_collation.php script.

I do not have a directory, "code/admin/cli/" but I do have, "admin/cli/mysql_collation.php"

Running this from the browser yields, "Command line scripts can not be executed from the web interface."

Running this from the command line as root/sudo yeilds,

root@server.locusplex.us [cli]# mysql_collation.php
bash: mysql_collation.php: command not found
root@server.locusplex.us [cli]# ./mysql_collation.php
bash: ./mysql_collation.php: Permission denied
root@server.locusplex.us [cli]# sudo ./mysql_collation.php
sudo: ./mysql_collation.php: command not found
root@server.locusplex.us [cli]# sudo mysql_collation.php
sudo: mysql_collation.php: command not found

> There are also 2 other DB scripts at location that might be worth checking.

Thanks for the help.

Patrick

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Re: Error: Database Connection Failed

by Ken Task - Sunday, December 27, 2020, 9:40 AM

/code/ was a place holder for path to your moodle code. No Vulcan Mind Meld possible from me.

Info for DB is MySQL 5.7. Yet in DB section of config.php I see an active variable meant not for MySQL - postgres? comment out - dbhandlesoptions?

DB server is localhost ... thus will use socket and thus 'dbsocket' should be ''; ... ie, blank ... no value. Ditto for port but one could leave that one ... won't hurt.

So section in config.php for DB should looks like:

$CFG->dboptions = array (
'dbpersist' => 0,
'dbport' => '',
'dbsocket' => '',
'dbcollation' => 'yourcollation',
);

The scripts in code/admin/cli/ for mysql are php scripts, thus to run them one has to issue: php scriptname.php

Run without options ... like "php mysql_collation.php [ENTER]" will bring up help for the script showing options to the script.

Like so:

[root@sos cli]# php mysql_collation.php

MySQL collation conversions script.

It is strongly recommended to stop the web server before the conversion.
This script may be executed before the main upgrade - 1.9.x data for example.

Options:
--collation=COLLATION Convert MySQL tables to different collation
-l, --list            Show table and column information
-a, --available       Show list of available collations
-h, --help            Print out this help

Example:
$ sudo -u www-data /usr/bin/php admin/cli/mysql_collation.php --collation=utf8mb4_unicode_ci

IF the DB host/credentials are correct, think the cli scripts would be able to run even if one could not use the Web interface.

Run the scripts anyway ... even if phpmyadmin appears to verify things phpmyadmin 'pages' info (25 at a time?) ... might be a page of info that shows some are not what they should be. The cli scripts do not page and some give a summary at the end of the run.

So, you are close ... but no cigar yet!

'SoS', Ken

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Re: Error: Database Connection Failed

by Patrick Masson - Sunday, December 27, 2020, 11:31 PM

Thank you so much for all the help. TL;DR, still no cigar. Details below.

But first, I noticed that when my hosting provider (Bluehost) restored the database ("locusple_schoolMoodle") and Moodle files after the OS upgrade (CentOS6 to 7), they incorrectly used the database name (locusple_schoolMoodle) as the privileged username for the Moodle database, instead of the actual database username. Therefore, while the config.php was correct, it was identifying a nonexistent user for the db.

I created a new database user (using the original db username) and assigned that user to the Moodle database (locusple_schoolMoodle) as a "Privileged User" and ensured the config.php file included the correct username and password. I also removed the nonexistent locusple_schoolMoodle user as a "Privileged User."

Unfortunately, that did not resolve the issue. However, I wonder if the restoration of the database after the upgrade with an incorrect user might have triggered the current issue?

Specific to your recommendations...

> /code/ was a place holder for path to your moodle code.

I assumed as much, but as I was restoring a backup, thought perhaps a directory might be missing. Just wanted to provide as much detail as possible.

> Info for DB is MySQL 5.7. Yet in DB section of config.php I see an active variable meant not for MySQL - postgres? comment out - dbhandlesoptions?

Commented out.

> DB server is localhost ... thus will use socket and thus 'dbsocket' should be ''; ... ie, blank ... no value. Ditto for port but one could leave that one ... won't hurt.

Removed both.

> So section in config.php for DB should looks like:

> $CFG->dboptions = array (
>'dbpersist' => 0,
> 'dbport' => '',
>'dbsocket' => '',
>'dbcollation' => 'yourcollation',
>);

As suggested...

> The scripts in code/admin/cli/ for mysql are php scripts, thus to run them one has to issue: php scriptname.php

> Run without options ... like "php mysql_collation.php [ENTER]" will bring up help for the script showing options to the script.

> Like so:
> [root@sos cli]# php mysql_collation.php

Running:

root@server.locusplex.us [cli]# php mysql_collation.php

Yields

!!! <p>Error: Database connection failed</p>
<p>It is possible that the database is overloaded or otherwise not running properly.</p>
<p>The site administrator should also check that the database details have been correctly specified in config.php</p> !!!

> MySQL collation conversions script.

> It is strongly recommended to stop the web server before the conversion.
> This script may be executed before the main upgrade - 1.9.x data for example.

> Options:
> --collation=COLLATION Convert MySQL tables to different collation
> -l, --list Show table and column information
> -a, --available Show list of available collations
> -h, --help Print out this help

> Example:
> $ sudo -u www-data /usr/bin/php admin/cli/mysql_collation.php --collation=utf8mb4_unicode_ci

Output:

Content-type: text/html; charset=UTF-8

!!! <p>Error: Database connection failed</p>
<p>It is possible that the database is overloaded or otherwise not running properly.</p>
<p>The site administrator should also check that the database details have been correctly specified in config.php</p> !!!

> IF the DB host/credentials are correct, think the cli scripts would be able to run even if one could not use the Web interface.

> Run the scripts anyway ... even if phpmyadmin appears to verify things phpmyadmin 'pages' info (25 at a time?) ... might be a page of info that shows some are not what they should be. The cli scripts do not page and some give a summary at the end of the run.

> So, you are close ... but no cigar yet!

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Re: Error: Database Connection Failed

by Ken Task - Monday, December 28, 2020, 12:33 AM

Debug lines from Section 7 of config-dist.php file can be inserted into active config.php file to get debug display.

//=========================================================================
// 7. SETTINGS FOR DEVELOPMENT SERVERS - not intended for production use!!!
//=========================================================================
//
// Force a debugging mode regardless the settings in the site administration
// @error_reporting(E_ALL | E_STRICT); // NOT FOR PRODUCTION SERVERS!
// @ini_set('display_errors', '1');    // NOT FOR PRODUCTION SERVERS!
// $CFG->debug = (E_ALL | E_STRICT);   // === DEBUG_DEVELOPER - NOT FOR PRODUCTION SERVERS!
// $CFG->debugdisplay = 1;             // NOT FOR PRODUCTION SERVERS!

Your output of the command line only script shows html tags. It shouldn't. Thus have to assume that from command line system is not finding php-cli which is not the same php executable used by the web service.

Don't use cPanel for the following ... ssh into server and as the user you have logged in with, issue:

php -v [ENTER] ... that's asking php to show version ..

IF system is finding php-cli response from above should look like:

PHP 7.2.34 (cli) (built: Oct 1 2020 13:37:37) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
with Zend OPcache v7.2.34, Copyright (c) 1999-2018, by Zend Technologies

Your PHP version ... but note the (cli) after version above.

which php [ENTER] - tries to find all registered with system php executables.

Might respond with /usr/bin/php

Try the -v switch using full path as above:

/usr/bin/php -v

Do you see (cli)?

IS /usr/bin/php really an alias that points to easy apache cli version?

That might be a question for hosting provider technical support.

Also, if moodle code is 3.10

Via command line one can check ... cd /path/to/moodlecode/

fgrep '$release' version.php

Also, with version 3.10 there is a environment check via CLI:

cd /path/to/moodlecode/admin/cli/

Then: php checks.php (if system finding php-cli, output hopefully shows:

OK: All 'status' checks OK

If not, what does it show?

'SoS', Ken

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Re: Error: Database Connection Failed

by Patrick Masson - Monday, December 28, 2020, 5:02 AM

>Debug lines from Section 7 of config-dist.php file can be inserted into active config.php file to get debug display.
> [...]

After uncommenting the lines in config.php, the following is reported...

Error

Error: Database connection failed
It is possible that the database is overloaded or otherwise not running properly.
The site administrator should also check that the database details have been correctly specified in config.php

Debug info: Access denied for user 'locusple_moodle'@'localhost' (using password: YES)
Error code: dbconnectionfailed

Stack trace:
    line 580 of /lib/dml/mysqli_native_moodle_database.php: dml_connection_exception thrown
    line 231 of /lib/dml/moodle_read_slave_trait.php: call to mysqli_native_moodle_database->raw_connect()
    line 217 of /lib/dml/moodle_read_slave_trait.php: call to mysqli_native_moodle_database->set_dbhwrite()
    line 340 of /lib/dmllib.php: call to mysqli_native_moodle_database->connect()
    line 630 of /lib/setup.php: call to setup_DB()
    line 1095 of /config.php: call to require_once()
    line 30 of /index.php: call to require_once()

> [...]
> php -v [ENTER] ... that's asking php to show version ..

# php -v
PHP 7.3.25 (cli) (built: Dec 23 2020 11:18:21) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.25, Copyright (c) 1998-2018 Zend Technologies

> IF system is finding php-cli response from above should look like:

> PHP 7.2.34 (cli) (built: Oct 1 2020 13:37:37) ( NTS )
> Copyright (c) 1997-2018 The PHP Group
> Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
> with Zend OPcache v7.2.34, Copyright (c) 1999-2018, by Zend Technologies

> Your PHP version ... but note the (cli) after version above.

I am thinking that I might be missing several PHP exceptions like OPcache specificly needed by Moodle. (remember, Bluehost wiped the server during the CentOS upgrade, so I suspect any customization to PHP and/or Apache were lost with the new OS install.

When I first installed Moodle, it reported several additional PHP extensions I needed. If those are missing (like OPcache was), perhaps that is an (the) issue. Is there a reference document I can review to see if all of the required extensions/plugins are installed?

> which php [ENTER] - tries to find all registered with system php executables.

# which php
/usr/local/bin/php

> Might respond with /usr/bin/php

Looks like I have a '/local/'. However, "ls /usr/bin/ph*" results in

# ls /usr/bin/ph*
/usr/bin/php

> Try the -v switch using full path as above:
> /usr/bin/php -v

Results:

# /usr/bin/php -v
PHP 7.3.25 (cgi-fcgi) (built: Dec 23 2020 11:18:59)
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.25, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.25, Copyright (c) 1999-2018, by Zend Technologies

> Do you see (cli)?

Nope. But using "/usr/local/bin/php", I do...

# /usr/local/bin/php -v
PHP 7.3.25 (cli) (built: Dec 23 2020 11:18:21) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.25, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.25, Copyright (c) 1999-2018, by Zend Technologies

> IS /usr/bin/php really an alias that points to easy apache cli version?

> That might be a question for hosting provider technical support.

I will check! If there is conflict with /usr/local/bin/php and /usr/bin/php where /usr/bin/php is being called, but not configued correctly, I assume that is not good.

Thank you for all the continued help,
Patrick

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Re: Error: Database Connection Failed

by Ken Task - Monday, December 28, 2020, 5:52 AM

Please see:

https://docs.moodle.org/310/en/PHP

for the other php extensions needed.

You could create a phpinfo.php script and place it in document root for your server ... where your moodle code resides or in your /school/ directory. Access directly with https://yourserver/school/phpinfo.php

That will show everything you didn't really wanna know about PHP - the web based php.

https://www.hostinger.com/tutorials/how-to-create-phpinfo-file

while not bluehost directions for creating a phpinfo.php script still apply.

/usr/local/bin/php is php-cli

/usr/bin/php is the executable for the web service.

https://www.bluehost.com/help/article/php-module

"Please note: VPS and Dedicated servers have fewer restrictions in regards to requesting and/or applying modules. If you are interested in upgrading your Shared Hosting account, check out our VPS or Dedicated Hosting packages."

and another clip from above url:

"Support does install PHP Versions or Modules upon customer request on VPS/Dedicated platforms if it's supported by cPanel (i.e. inside of the EasyApache4 interface)."

'SoS', Ken

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Re: Error: Database Connection Failed

by Ken Task - Monday, December 28, 2020, 1:51 AM

In addition, see in config.php file that DB collation is set to utf8_whatever.

The 'future' of moodle DB's (from what I read) is utf8mb4 character set with utf8mb4_unicode_ci collation.

If php-cli can be found, a script in code/admin/cli/ will help with collation of DB:

cd /path/to/moodlecode/admin/cli/

and if php-cli is being used, issue:

php mysql_collation.php --list

That will scroll a bunch of tables (all tables in moodle DB and columns are displayed). Summary at end should show something like:

Table collations summary for https://yourserver/path/to/moodle/:
utf8mb4_unicode_ci: 1578

The number shown above is the number of tables. If there are other tables that have a different collation, script will list in the summary how many tables have what collation. Note: number of tables might be different for your server depending upon addons's and plugins ... above from a site that has very vew addons ... thus fewer tables than a site that had a bunch of addons/plugins.

It is possible that some tables ... not all .. have a mis-match.

Same script, BTW, can fix.

Collation in DB needs to match the collation that's in config.php

This sort of thing is what I was talking about when saying moodle is a beast to itself ... no such requirements for WordPress, or MediaWiki, nor any CMS of which am aware. But, setting character set/collations via MySQL 5.7.x config file to be defaults for the Moodle DB, *might upset* WordPress, MediaWiki, etc. database/tables.

Official Moodle docs:

https://docs.moodle.org/310/en/MySQL_full_unicode_support

'SoS', Ken

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Re: Error: Database Connection Failed

by Visvanath Ratnaweera - Sunday, December 27, 2020, 3:29 PM

Did you look at the debug trace?

Can't see this information Ken has requested:

> Bluehost VPS - is it managed or unmanaged?
>
> Is this a standalone server where the DB server is on the same machine?

And this is a fresh installation, which never ran (under load), right? If so, it can't be a performance issue (this is Hardware and performance forum), there is a separate forum for installation problems.

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Re: Error: Database Connection Failed

by Patrick Masson - Sunday, December 27, 2020, 11:45 PM

Hi Visvanath.

Thank you for the reply.

> Did you look at the debug trace?

I can't get onto Moodle (Site administration > Development > Debugging) to run the trace through the Admin panel. Not sure if there is another way to do this? All suggestions appreciated.

> Can't see this information Ken has requested:
>> Bluehost VPS - is it managed or unmanaged?

Bluehost provides managed hosting (VPS), but not any services for Moodile.

>> Is this a standalone server where the DB server is on the same machine?

Yes.

> And this is a fresh installation, which never ran (under load), right? If so, it can't be a performance issue (this is Hardware and performance forum), there is a separate forum for installation problems.

The original installation was Nov. 27, 2020. The site was running as expected until Dec. 23rd when the OS was updated from CentOS 6 to CentOS 7. A full backup was made prior to the OS upgrade (by me). The server was then wiped and a new one created running CentoOS7 (by Bluehost--the hosting provider), and the backups were restored (by Bluehost). All other services, mail, NextCloud, MediaWiki (all using same backup files and running the same PHP version and using the same MySQL instance) are running as expected.

Thanks again for the help - Patrick

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Re: Error: Database Connection Failed

by Ken Task - Monday, December 28, 2020, 4:23 AM

Well ... progress in discovery ... with debug now active ..

Debug says:

Debug info: Access denied for user 'locusple_moodle'@'localhost' (using password: YES)

line 231 of /lib/dml/moodle_read_slave_trait.php: call to mysqli_native_moodle_database->raw_connect()

So it might be that there are more lines active in config.php than need be for current hosting.

In same section of config.php where one is defining DB parameters, do you have a slave.dbhost line active?

For all database config settings see https://docs.moodle.org/en/Database_settings

'SoS', Ken

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Re: Error: Database Connection Failed

by Ken Task - Monday, December 28, 2020, 6:59 AM

Oops .. forget that url to DB settings ... was/is about Database activity in Moodle and not over all database set up for site.

One last suggestion ... review all of your config.php file ... what's active and find out/know why items are active. If you have issues with site once this is resolved, go back to config.php file and check ... no Vulcan Mind Melds possible! :|

'SoS', Ken

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Re: Error: Database Connection Failed

by Visvanath Ratnaweera - Monday, December 28, 2020, 6:17 PM

Hi

You wrote:
>> Did you look at the debug trace?
> > I can't get onto Moodle (Site administration > Development > Debugging) to run the trace through the Admin panel. Not sure if there is another way to do this?

Ken answered this already: https://moodle.org/mod/forum/discuss.php?d=415337#p1675944.

>>> Bluehost VPS - is it managed or unmanaged?
> > Bluehost provides managed hosting (VPS), but not any services for Moodile.

I am not interested in what Bluehost provides. The question was about your server. Is it:
a) a VPS/dedicated which you manage?
b) a VPS/dedicated which Bluehost manages?
c) a VPS/dedicated which both manage?

>>> Is this a standalone server where the DB server is on the same machine?
> > Yes.

Good.

>> And this is a fresh installation, which never ran (under load), right? If so, it can't be a performance issue (this is Hardware and performance forum), there is a separate forum for installation problems.

> The original installation was Nov. 27, 2020. The site was running as expected until Dec. 23rd when the OS was updated from CentOS 6 to CentOS 7. A full backup was made prior to the OS upgrade (by me).

Looks like, both mange the server, which makes matters complicated.

> The server was then wiped and a new one created running CentoOS7 (by Bluehost--the hosting provider), and the backups were restored (by Bluehost). All other services, mail, NextCloud, MediaWiki (all using same backup files and running the same PHP version and using the same MySQL instance) are running as expected.

Could be missing PHP modules in the new OS. Again, Ken is following that line: https://moodle.org/mod/forum/discuss.php?d=415337#p1675971.

I don't have anything to add other than that you are in the wrong forum. This is an installation problem, not a performance problem.

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Re: Error: Database Connection Failed

by Mary Cooch - Monday, December 28, 2020, 6:31 PM

Just moving this to the Installing and upgrading help forum...

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[CLOSED] Re: Error: Database Connection Failed

by Patrick Masson - Tuesday, December 29, 2020, 3:51 AM

Thanks to all for your kind help. As things are now so convoluted, I am going to simply wipe Moodle, do a fresh install, and then restore my backups.

Thanks again for the help: Moodle is great but the community makes it the best

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Re: [CLOSED] Re: Error: Database Connection Failed

by Ken Task - Tuesday, December 29, 2020, 5:24 AM

Looking through a big config.php can be daunting ... one will learn a lot ... but ... since this has been hanging around with no resolution, before you wipe out your migrated site, how about a minimal config file?

Download:

https://sos.sosoftexas.org/mdlcfgmin.txt

to the document root of your moodle code.

cd /path/to/moodlecode/

wget https://sos.sosoftexas.org/mdlcfgmin.txt

move your current config.php to an archive ...

mv config.php config.php.archive

copy the mdlcfgmin.txt file to config.php

cp mdlcfgmin.txt config.php

Then edit and fill in what's missing:

nano config.php

Debug lines are contained the file are commented out and you can activate them by removing the // in front of them.

Save the file.

Make sure it is readable by all:

chmod ugo+r config.php

Try your site via web.

Going the route you say you are going to take ... installing fresh instance ... getting that working ... and then restoring your site backup files/DB/moodledata could be just as confusing if one also restores the same config.php file from old site.

Think I'd try the path of least amount of work first.

'SoS', Ken

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Re: [CLOSED] Re: Error: Database Connection Failed

by Visvanath Ratnaweera - Tuesday, December 29, 2020, 5:24 PM

After so much praise can't let go.

Seriously, there are technical reasons too. We have a strong clue of the cause: It is the system upgrade. (I'm assuming that your provider hasn't moved your site to a new machine, nor completely wiped out the old system and installed the new system. Nobody does that. Rather it was a "dist upgrade" through scripts provided by CentOS.) Moodle won't restart in new system could only mean that some critical components are missing. Then the solution is simple; Install the missing parts.

The focused method is to find out (through debugging and phpinfo) what exactly is missing. If that is too tedious, you can try a fuzzy method by starting to install PHP modules. The compulsory ones for rel. 3.9 are iconv, mbstring, curl, openssl, ctype, zip, zlib, gd, simplexml, spl, pcre, dom, xml, xmlreader, intl, json, hash, fileinfo, xsl and mysqli. That'll take off Moodle just enough to report further problems through its GUI.

There could be second reason: That your hosting provider is involved in the process. The "big" generic hosting providers don't know Moodle. What they care is WordPress, which is hundred times simpler. And the worst part, they are used to tighten ("harden") the server for WordPress. If such an unknown (to us) precautionary measure is blocking Moodle, it is not going to leave. You'll be back at square one.

And you will be doing the helpers a favour by digging the cause. Letting go leaving it for speculation is not a good feeling. So, if you haven't already wiped out Moodle, follow the detailed instructions in Ken's previous post.

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Re: Error: Database Connection Failed

by Visvanath Ratnaweera - Tuesday, December 15, 2020, 2:53 AM

Well, your server environment may have a network issue. But why does the database server need to resolve the IP of clients? Run a web search for "mysql skip-name-resolve performance".

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