Moodle in English: blank page after restoring a backup, why ?

blank page after restoring a backup, why ?

by pierre REMY - Tuesday, November 12, 2019, 7:01 PM

hi,

i tried to update my moodle 3.5.2 to the last 3.5.9.

After i finished the procedure, there is a blank page once i visit the webpage.

So i think there was a fail and i decided to restore my old 3.5.2 backup (the full www folder). i guess the database did not change between 3.5.2 and 3.5.9 so, i did not recover it. Even not, i did not recover the moodledata wich may not impacted by the update.

so, what is the problem ? why this bank page (with no html code source), no error.

Apache is started, and mysql too. Restarted toot.

what did i miss ? why this blank page ?

Best regards.

Pierre

Re: blank page after restoring a backup, why ?

by Emma Richardson - Tuesday, November 12, 2019, 9:44 PM

Ok, well you can't just restore the moodle code folder. There are changes to the database and moodledata folder with every upgrade. The white page could just be indicative of needing a cache clear or could be a php issue. Turn debugging on in your config.php file (instructions in docs) and see if it gives you a clue...

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Re: blank page after restoring a backup, why ?

by Justin Hunt - Tuesday, November 12, 2019, 9:48 PM

Pierre,

There are many possible errors that can cause the blank page.

If you were able to perform the upgrade using Moodle's upgrade wizard, and then it went black, it sounds like an error in PHP. In that case you should turn on debugging for your site. You will see an error displayed instead of just blank page. That should lead you to the problem. To turn on debugging, in your config.php file, uncomment (or add) these lines. You will find them under "7. SETTINGS FOR DEVELOPMENT SERVERS - not intended for production use!!!":

 @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!

If you were not able to perform the upgrade, because as soon as you copied or pulled the new Moodle version into your site it went blank, then it could be you put the files in the wrong place or your files now have incorrect file permissions/ownership.

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Re: blank page after restoring a backup, why ?

by pierre REMY - Wednesday, November 13, 2019, 12:10 AM

hi,
well i added the lines :
@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!

but there is always the blank page...
i'll try to find logs on the server side...

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Re: blank page after restoring a backup, why ?

by pierre REMY - Wednesday, November 13, 2019, 12:45 AM

i'm saved !
well it was the permissions/owners !
Justin Hunt, you were just right !

althought the debugging options are enabled, there were no message.
Poor me, the official debug documation did not remind to check the permissionw/owners.

My restoration did not work because when i copy as root, i did not thing about restore the original owner/group.
So in ssh (via putty64), i just perform :
chown -R originalUser:originalUser www
and the website is back !

The official 3.5 debbug page should be complete to refer the ower/group/permission things, it will help !

https://docs.moodle.org/35/en/Debugging#Debug_messages

even the last release doc did not mention this point to make the debugg running.

https://docs.moodle.org/38/en/Debugging#Debug_messages

well, i will sleep well now.

thank you all

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Re: blank page after restoring a backup, why ?

by Visvanath Ratnaweera - Wednesday, November 13, 2019, 4:42 AM

Two details, in case you've missed:
- The syntax of chown is chown -R USER:GROUP /some/path
- The originalUser in your chown is no supposed to be the owner of the web server processes.

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Re: blank page after restoring a backup, why ?

by Justin Hunt - Wednesday, November 13, 2019, 7:02 AM

OK. Thats good. The reason you did not see any debug error messages from php at all, is that the web server could not even open the php files to run them. It never even got to those lines in config.php.

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Re: blank page after restoring a backup, why ?

by Asher Baig - Thursday, July 2, 2020, 5:24 AM

Can you elloborate, i got exactly same problem

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blank page after restoring a backup, why ?