If you are using WordPress on a ISPConfig3 hosting solution with PHP-FPM, you may be limited to 2MB upload size.
Error message :
Maximum upload file size: 2MB. After a file has been uploaded, you can add titles and descriptions.
filename.pdf exceeds the maximum upload size for this site.
Update : With ISPConfig 3.1 dev, on a system with CentOS 7.4 and apache + php-fpm 5.4 you have to edit /etc/php.ini and set post_max_size and upload_max_filesize to 32 MB.
Restart apache & php-fpm.
To solve this you need to edit the php.ini file located in
/etc/php5/cgi/php.ini instead of the classic
Edit the lines below and change 2M to 50M:
; Maximum allowed size for uploaded files. ; http://php.net/upload-max-filesize upload_max_filesize = 50M ... ; Maximum size of POST data that PHP will accept. ; http://php.net/post-max-size post_max_size = 50M
Restart Apache2, then relogin to WordPress.
Also see this post if you are running PHP-FPM which may also limit you.