Experiencing 500 Internal Server Errors on WordPress after Package Update?

Redhat Enterprise 6 and fatal error with Wordpress

Segfaults in libfreeblpriv3.so after upgrading to RHEL 6.8 – illegal instruction

If you are like us and experienced 500 Internal Server Errors on your WordPress installation after a package update, we tracked the cause of the errors in the WordPress installation to be HTTPS Requests being made by cURL.

This issue could affect you if the following apply:

  • Red Hat Enterprise Linux (RHEL) 6.8
  • XEN Hypervisor
  • AES flag set

Curl, Python, PHP, Perl, Java, etc. — the web libraries associated to these are all affected.

Temporary Fix

Get WordPress online ASAP

Add this line:
putenv("NSS_DISABLE_HW_AES=1");

To the top of these files:
index.php
wp-cron.php
wp-load.php
/wp-admin/admin.php

Additional details

You can downgrade the affected packages. However, if that is not an option for you at this time then you can get back up and running by setting NSS_DISABLE_HW_AES=1.

Keep in mind that this only applies for the current session so it will  be best to have a script set this for you.

Some of the errors you might be seeing

500 Internal Server Error

curl https://www.google.com
Illegal instruction


yum update
Loaded plugins: fastestmirror
Setting up Update Process
Loading mirror speeds from cached hostfile
Illegal instruction


[Mon Jun 06 20:31:14 2016] [error] [client *.*.*.*] Premature end of script headers: php5.cgi, referer: http://whatever.com/wp-admin/

[Mon Jun 06 22:02:55 2016] [warn] [client *.*.*.*] (104)Connection reset by peer: mod_fcgid: error reading data from FastCGI server
[Mon Jun 06 22:02:55 2016] [error] [client *.*.*.*] Premature end of script headers: testcurl.php


[Mon Jun 06 20:31:14 2016] [error] [client *.*.*.*] Premature end of script headers: php5.cgi, referer: http://whatever.com/wp-admin/

[Mon Jun 06 23:34:49 2016] [warn] [client *.*.*.*] (104)Connection reset by peer: mod_fcgid: error reading data from FastCGI server
[Mon Jun 06 23:34:49 2016] [warn] [client *.*.*.*] (104)Connection reset by peer: mod_fcgid: ap_pass_brigade failed in handle_request_ipc function

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