Unable to attach files in a WebMail or any file upload when ModSecurity is active: An error occurred! File upload failed

Symptoms

• Unable to attach files bigger than 15MB in webmail with following error:

  An error occurred! File upload failed

• Drag and drop file into webmail body message fails with following error:

  Server error! (Request Entity Too Large)

• Unable to attach big files to the website forms with the error below:

  Connection to the server failed

• Following error message is shown in Apache log file:

  # tail -f /var/log/httpd/error_log
  [:error] ModSecurity: Request body (Content-Length) is larger than the configured limit (13107200). [hostname “webmail.example.com”] [uri “/”] [unique_id “Wvm2-f069f312c27e”], referer: http://webmail.example.com/?_task=mail&_action=compose&_id=123456789abcdefgh

• ModSecurity SecRequestBodyLimit parameter is set as follows:

  # egrep -Ri SecRequestBodyLimit /etc/httpd/conf.d/mod_security.conf
  SecRequestBodyLimit 13107200

Cause

Upload file process fails because ModSecurity SecRequestBodyLimit is reached.

Resolution

1. Log in to Plesk.

2. Navigate to Tools & settings > Web Application Firewall (ModSecurity) > Settings > Custom directives:

3. Add the field

   SecResponseBodyLimit 67108864

4. Press Apply