Hello everyone!
I recently came to be the admin of an existing Moodle installation. While checking the site handed to me, I noticed that cron hadn't run in a *very* long time. The site has been updated twice(!) while cron was not running, too.
I added cron to the crontab on the server and let it run manually in a console. It took about a minute to finish everything and send out emails.
At first, I thought everything was fine, but soon I noticed that Moodle would display a database error whenever cron had been run recently. Then it would take about a minute for Moodle to spring back to life without any intervention.
In case of admin/index.php?cache=0, the he error shown would be this:
Fehler beim Lesen der Datenbank
Debug info: Lost connection to MySQL server during query
SELECT * FROM mdl_context WHERE contextlevel = ?
[array (
0 => 10,
)]
Error code: dmlreadexception
SELECT * FROM mdl_context WHERE contextlevel = ?
[array (
0 => 10,
)]
Error code: dmlreadexception
Stack trace:
- line 486 of /lib/dml/moodle_database.php: dml_read_exception thrown
- line 1273 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
- line 1671 of /lib/dml/moodle_database.php: call to mysqli_native_moodle_database->get_records_sql()
- line 1643 of /lib/dml/moodle_database.php: call to moodle_database->get_record_sql()
- line 1622 of /lib/dml/moodle_database.php: call to moodle_database->get_record_select()
- line 6308 of /lib/accesslib.php: call to moodle_database->get_record()
- line 758 of /lib/setup.php: call to context_system::instance()
- line 27 of /config.php: call to require_once()
- line 88 of /admin/index.php: call to require()
I also got the following error, when I change the cache parameter from 1 to 0:Error reading from database
Coding error detected, it must be fixed by a programmer: block_manager has not yet loaded the blocks, to it is too soon to request the information you asked for.
Afterwards, the cron job would often print an error message regarding the database, also executing this query:
SELECT * FROM mdl_context WHERE contextlevel = ?
[array (
0 => 10,
)]
What could cause such misery? Is the database corrupted due to the cron not running for so long or could it be something else?We are using Moodle 3.10.3+ (Build: 20210430) with MariaDB.