Segmentation fault on certain WordPress pages on Ubuntu / Apache / PHP

  • Posted on February 3, 2015
  • dimatxAsked by Dima

I’m getting reproducible errors when trying to access certain parts of a WordPress instance. This identical behavior occurs on two WordPress instances hosted on the same box.

The two actions that fail (and lead to an error page in Chrome (Error code: ERR_EMPTY_RESPONSE), and an error logged on server) are:

  • Attempting to access the “General” settings page (/wp-admin/options-general.php)
  • Attempting to confirm the deletion of any plugin

Apache2 error.log:

[core:notice] [pid 9173] AH00052: child pid 9181 exit signal Segmentation fault (11)```

Server Info:
```Ubuntu 14.04.1 LTS (GNU/Linux 3.13.0-24-generic x86_64)```

```PHP 5.5.9-1ubuntu4.5 (cli) (built: Oct 29 2014 11:59:10)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
    with Zend OPcache v7.0.3, Copyright (c) 1999-2014, by Zend Technologies
    with Xdebug v2.2.3, Copyright (c) 2002-2013, by Derick Rethans```

Please let me know what other information may be helpful. Thanks in advance.
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I found a fix for this, it requires a patch update of libssh2-php. See this thread here:

apt-get source libssh2-php
cd php-ssh2-0.12/
apt-get build-dep php-ssh2
apt-get install build-essential fakeroot devscripts
patch -p1 < fix-segfault.patch 
rm fix-segfault.patch 
debchange -i
dpkg-buildpackage -b

Restarted my Droplet (you could probably just restart Apache) and it works now!

After an entire day of trying to trace this down, no solutions worked. I eventually however turned Apache to debug level logging and immediately noticed hundreds of notices/warnings with Google’s mod_pagespeed for Apache trying to rewrite images from Jetpack’s Photon images.

I did a simple a2dismod pagespeed and immediately there were no more segmentation faults.

Have also noticed my sites are actually running faster now with mod pagespeed turned off.

There seems to be quite a few bug reports about pagespeed causing segmentation faults.

Not sure if its just mod_pagespeed or the combination of mod_pagespeed, wordpress and php … but turned off now problem gone.

I am done with it for now and in the process of moving everything to Nginx now. Tracing faults on Apache always turns into a nightmare, with Nginx I can find errors in a few seconds to a minute. Already spent the last 6 weeks getting to know Nginx and it rocks and now going back to my Apache server to try and diagnose this segfault error felt like I was in a different world where I could not speak the language anymore.

you absolute legend this fixed and issue i was having with a script!!