Ok so I decided to quickly make this post because it was such a bitch to figure this out, all the information regarding missing dynamic libraries are in many cases unclear and could not find anything specific on the mcrypt library.
if you get the:
“PHP Startup: Unable to load dynamic library ‘/usr/lib/php5/20090626/mcrypt.so’ – libmcrypt.so.4: cannot open shared object file: No such file or directory in Unknown on line 0”
Here is whats going on…
you are missing files that are part of Apaches/PHP’s resources or you php.ini has the “entension_dir” value duplicated/actively pointing to the wrong location or php-cli is using the wrong php.ini config file. In my case it was due to a glitch with Ubuntu servers live OS update to 12.04.1 LTS which removed the old libraries and never re-installed them as part of the update.
Here is the checklist that will save you a long-ass headache, one that I unfortunately went through…
1) check your php.ini and make sure your “extension_dir” value (typically between line 805-809) is nulled out so its not processed (usually has a ; in front of it) in some cases the php.ini can be in multiple locations for apache/php-cli etc…
2) your mcrypt.so library is missing or corrupt.
first lets remove any possible installations of mcrypt libraries by running this in a shell, if you don’t have it installed skip this step (or you can still do it and if its not installed it will do nothing)…
sudo apt-get remove php5-mcrypt
sudo apt-get purge php5-mcrypt
then run this in a shell…
apt-get install php5-mcrypt (or you can sudo reboot too ;))
/etc/init.d/apache2 restart
once this is done you should no longer get this error. If you have any issues please leave me a comment below :)