Blank page when loading moodle

Blank page when loading moodle

by J Skeleton -
Number of replies: 6

Hi all,

I migrated a Moodle install from a hosted solution to a TurnKey Linux Moodle appliance on an in-house VMWare ESXi server.

As part of the migration, I upgraded to 2.7+ (Build: 20140703). I believe the previous server was on 2.5. It worked fine for a few days and then started just displaying a blank page for everything except the login page. However, when trying to login, it'd just go to a blank page after that.

Chrome gives the error: "Error code: ERR_EMPTY_RESPONSE" and about the only other thing I can find is an entry that pops up in the apache error log that says:

[Mon Jul 07 08:06:09 2014] [notice] child pid 13311 exit signal Segmentation fault (11)

every time the blank page is displayed.

After trying all sorts of things last week, I finally wiped out the Moodle program files (not the DB or moodledata folder) and reinstalled. I ran setup which linked it back to the db and moodledata. It was working fine again at that point. I just checked it again this morning and it's doing the same thing again.

I've tried enabling more debugging but I haven't gotten any more info or I'm looking in the wrong place

PHP 5.4.4-14+deb7u11 (cli) (built: Jun 13 2014 13:53:15) 
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies
with XCache v2.0.0, Copyright (c) 2005-2012, by mOo
mysql  Ver 14.14 Distrib 5.5.37, for debian-linux-gnu (x86_64) using readline 6.2

Thanks for any assistance you can give

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In reply to J Skeleton

Re: Blank page when loading moodle

by Howard Miller -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers

This is almost certainly not a Moodle problem per se, it is something wrong in the server setup. These errors can be very difficult to track down unfortunately. 

I would try removing or switching off anything you don't need. Start with XCache. Where did the PHP come from? Is this standard Debian PHP or compiled from source or something else? Make sure you have the latest version / patches (of everything)?

Have you got enough RAM? Are your php.ini settings sensible and/or as recommended in the Moodle release notes?

Make sure you have Debugging turned up full, although it probably won't tell you anything. 

I've found myself in the past having to breakpoint my way through masses of Moodle code to work out exactly what statement it fails at. Even then it only gives you a clue.

Let us know how you get on!

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In reply to Howard Miller

Re: Blank page when loading moodle

by J Skeleton -

Yeah, I was starting to think it was more server than Moodle - PHP specifically but I'm not great at PHP debugging.  The server is courtesy of Turnkey Linux -- I posted a link in my original post. They put together VM appliances with a nice web UI. I used their Moodle appliance, but I did upgrade Moodle after installing it so maybe that's what broke it.

Memory should be fine. I believe it's set at 32mb in php.ini. The server itself has 8GB to play with.

Looked in some access logs and I saw /Calendar stuff and I found that I can load links like: http://moodle.server.address/calendar/view.php?view=month&course=1&time=3103077600 and the link to http://moodle.server.address/course/index.php brings up the course listings. It's when I click on any of those, I get the login page and then the blank page.

So seems like something on the front page is erroring out. Very weird that it'll start working and then stop for some reason.

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In reply to J Skeleton

Re: Blank page when loading moodle

by Howard Miller -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers

32mb is not nearly enough. Change it to 512mb and see if it makes any difference. Don't be tempted to put in some crazy big number "just to try it" wink

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In reply to Howard Miller

Re: Blank page when loading moodle

by J Skeleton -

No dice... I actually tried loading an entirely different Moodle Appliance and got the same result... Worked for a few hours and then died. No idea where to go from here.

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In reply to J Skeleton

Re: Blank page when loading moodle

by Howard Miller -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers

It's really your hosting company's problem. Don't let them tell you that it must be Moodle. It works for (just about) everybody else. 

If the configuration is ok then it often comes down to a rogue build of PHP - some incompatible version of a library or similar. As I say, unless you get lucky it can be very hard to find. 

I'm trying to get my head around what this "Turnkey" thing is. Why not just install Moodle yourself on an Amazon VM? That works - I've got lots of them running. We don't recommend these one-click style solutions for absolutely this reason. It's very hard to help if it goes wrong as we have no idea how it's set up.

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In reply to Howard Miller

Re: Blank page when loading moodle

by Felipe Fert -

fix by changing xcache.cacher to Off in /etc/php5/apache2/conf.d/20-xcache.ini and restarting Apache.

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