This usually happens due to a resource issue, conflict between plugins, or a setting on your server that needs to be adjusted. The easiest way to fix this issue is to reach out to your host. You can also do this yourself if you’re comfortable editing your site files.
You can try the following methods:
1. Edit wp-config.php file
Look for this line to edit the memory limit:
Modify this parameter by increasing it. PHP memory limit of 256M should be enough.
That’s it, now save the file.
2. Edit .htaccess file
To increase the PHP memory, add the following to your .htaccess file:
php_value memory_limit 256M php_value upload_max_filesize 12M php_value post_max_size 13M
3. Edit PHP.ini file
To increase the PHP memory limit and execution time, change these lines in PHP.ini
memory_limit = 256M post_max_size = 13M file_uploads = On max_execution_time = 180