We know, it’s been a couple of weeks since we last wrote a post on this blog – we’re not getting lazy, it’s just that we had quite a few large projects in December. Still, we feel guilty, and so we decided to write a post right now, and if you want to know what right now is, then it is 8:52 PM EST on December 31^st, 2016. Yes, it’s new year’s eve, and we’re writing a blog post!

OK – enough with this introduction. Let’s start with the juicy stuff…

As a Joomla administrator, you may have seen one of the following errors on your Joomla website (or maybe you have seen both of them):

Fatal error: Allowed memory size of x bytes exhausted (tried to allocate x bytes)

Fatal error: Out of memory (allocated x) (tried to allocate x bytes)

To the untrained eye, the above errors look more or less the same: they look like a memory problem, and this is correct, they are memory issues. But, they are completely different memory issues. Unfortunately, most Joomla administrators think that the above errors are the same, and they think that the solution presented in this post will fix both of them. This isn’t the case…

In fact, increasing the memory_limit in the php.ini or the .user.ini file may address the first problem, but it certainly will not address the second problem. You see, the first problem means that the Joomla website has exceeded the allowed memory limit for the PHP instance, while the second problem means that the Joomla website has used up all the available memory. Let us give you an example…

Say your default php.ini has a memory limit of 32 MB, and say you have 2 GB of RAM on your server… If a page on your Joomla website exceeds 32 MB, then you will see the Allowed memory… fatal error. However, if the memory limit in your php.ini file is set to a very high number, like 4096 MB (or 4 GB, which should never be the case), and you have 2 GB of RAM on your server, then if a page on your Joomla website needs more than 2 GB, then you will see the Out of memory fatal error.

Now, if you read the above paragraph very carefully, then your question would be, why would anyone, in a real life scenario, see the Out of memory fatal error? Good question!

In fact, in a real life scenario, the Out of memory fatal error is never thrown because all of the server’s memory was exhausted, it is thrown because a hard limit set at the Apache level is exceeded, and that hard limit is set using the RLimitMEM directive in Apache. For example, having the following in your httpd.conf file…

RLimitMEM 33554432

…means that there is a hard limit of 32 MB on the memory usage on your Joomla website, which means that any page on your Joomla website needing more than 32 MB will throw the Out of memory fatal error (assuming the PHP memory_limit is higher than 32 MB, otherwise, the page will throw an Allowed memory fatal error).

So, how to address an “Out of memory” fatal error?

Obviously, addressing such an error can be done by either commenting out the whole RLimitMEM line in the httpd.conf file, or by increasing the value of RLimitMEM (also in httpd.conf) to a higher value, and then restarting Apache. Note that if you’re using WHM, you can change the value of RLimitMEM from within WHM, here’s how:

• Login to the WHM console as root.

• In the search box on the top left, search for Apache Configuration.

• Click on Apache Configuration.

• Scroll down a bit and click on Memory Usage Restrictions.

• In the Configure Apache RLimits page, you can either disable RLimitMEM or you can just set it to a higher value. Note that you will need to restart Apache for the settings to take effect.

If you’re seeing the problem and you are on shared hosting, then you should contact your hosting company, and they may increase it for you (but don’t hold your breath, as they most likely won’t).