I am trying to upload image/video to the post and receiving this error message. Hence, I have searched the solutions and fix my problem. I think many of the wordpress users are receiving this type of error message. Hence, I have decided to share the solution here to overcome their problem.
1) Either rename/remove Plugins folder via FTP or disables all the Plugins from database
2. If you have an access of PHP.ini file of the account/server then change the line in PHP.ini where line shows 32M to 64M:
memory_limit = 64M; Maximum amount of memory a script may consume (64MB)
3. If you do not have access of PHP.ini file then add this to an .htaccess file of your domain:
php_value memory_limit 64M
4. Try to add this line to your wp-config.php file to increase allocated memory to PHP:
If all this option can not resolve the issue then you need to contact your hosting service provider to resolve this issue.