I have used almost 3 days trying to hunt down, why some of my WP-sites have been limited to 256MB PHP memory. Today I found out that when Festinger Vault i activated, then I am having this issue.
When I deactivate the plugin, then I am back on 2048MB.
This can be found through the Festinger Vault plugin while you edit the code.
WP dashboard → Plugins → Plugin Editor
Wp-config.php is one of the most important WordPress files because it contains your base configuration details. You’ll find it in the root of your WordPress file directory.
To edit the memory limit and upload limit, look for this line:
define('WP_MEMORY_LIMIT', '32M');
This limit can be changed from your WP-Config.
Modify the second parameter by increasing it. As I mentioned a PHP memory limit of 128M should be more than enough.
define('WP_MEMORY_LIMIT', '128M');
Save the file and you’re done. You may need to increase it again if you’re still getting the fatal error, but don’t go overboard or you may crash your server. All the more reason to reach out to your host for help.