Allowed memory size of X bytes exhausted

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 13965430 bytes)

PHPInfo shows that I have a memory_limit of 128M, so I'm confused as to why the error says I only have 64M. Is it possible for phpinfo to report incorrectly? Or for PHP to use two separate php.inis?

The error was being caused by an ini_set call in one of the primary php files that a co-worker of mine added without my knowledge.

PHP's config can be set in multiple places:

1. master system php.ini (usually in /etc somewhere)
2. somewhere in Apache's configuration (httpd.conf or a per-site .conf file, via php_value)
3. CLI & CGI can have a different php.ini (use the command php -i | grep memory_limit to check the CLI conf)
4. local .htaccess files (also php_value)
5. in-script (via ini_set())

In PHPinfo's output, the "Master" value is the compiled-in default value, and the "Local" value is what's actually in effect. It can be either unchanged from the default, or overridden in any of the above locations.

Also note that PHP generally has different .ini files for command-line and webserver-based operation. Checking phpinfo() from the command line will report different values than if you'd run it in a web-based script.

ini_set('memory_limit', '128M'); 

or

php.ini  =>  memory_limit = 128M

or

php_value memory_limit 128M

I had same issue. I found the answer:

ini_set('memory_limit', '-1');

Note: It will take unlimited memory usage of server.

Update: Use this carefully as this might slow down your system if the PHP script starts using an excessive amount of memory, causing a lot of swap space usage. You can use this if you know program will not take much memory and also you don't know how much to set it right now. But you will eventually find it how much memory you require for that program.

You should always memory limit as some value as answered by @şarkı dinle.

ini_set('memory_limit', '512M');

Giving unlimited memory is bad practice, rather we should give some max limit that we can bear and then optimise our code or add some RAMs.

The memory must be configured in several places.
Set memory_limit to 512M:

sudo vi /etc/php5/cgi/php.ini
sudo vi /etc/php5/cli/php.ini
sudo vi /etc/php5/apache2/php.ini Or /etc/php5/fpm/php.ini

Restart service:

sudo service service php5-fpm restart
sudo service service nginx restart

or

sudo service apache2 restart

Finally it should solve the problem of the memory_limit

If you're sure you restarted Apache after configuring php.ini, then you might be looking at the wrong php.ini file