RoundCube shows error when sending email with attachment: An error occurred: Request timed out

Symptoms

• RoundCube shows error when sending email with attachment with file size more than 20 MB. The following error appears in Plesk UI:
  

• Emails are delivered regardless the above error.

• Plesk > Tools & Settings > Mail server settings > Maximum message size value is set to 20 MB or more.

• The following error appears in /var/log/nginx/error.log when sending email:

  [error] 19201#0: *11874 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 203.0.113.2, server: webmail.example.com request: "POST /roundcube/?_task=mail&_unlock=loading123456789000&_lang=en_US&_framed=1 HTTP/2.0", upstream: "https://203.0.113.2:7081/roundcube/?_task=mail&_unlock=loading123456789000&_lang=en_US&_framed=1", host: "webmail.example.com", referrer: "https://webmail.example.com/roundcube/?_task=mail&_action=compose&_id=123456789000"

• The following error appears in /var/log/apache2/error.log:

  [fcgid:warn] [pid 12345:tid 123456789000] [client 203.0.113.2:51272] mod_fcgid: read data timeout in 45 seconds, referer: https://webmail.example.com/roundcube/?_task=mail&_action=compose&_id=123456789000

Cause

Insufficient timeout time values for FastCGI PHP engine.

Resolution

1. Connect to the server via SSH as root.

2. Create the file: /etc/nginx/conf.d/customdirectives.conf and add the following lines to it

   proxy_send_timeout 1200s;
   proxy_read_timeout 1200s;
   fastcgi_send_timeout 1200s;
   fastcgi_read_timeout 1200s;

3. Reload nginx configuration:

   # service nginx reload

4. Edit the corresponding configuration file to increase the FcgidIOTimeout value to 250 seconds or more. Vi editor can be used:

   For Debian / Ubuntu:

   /etc/apache2/mods-enabled/fcgid.conf

   For CentOS / RedHat / CloudLinux

   /etc/httpd/conf.d/fcgid.conf

5. Reload Apache service:

   For Debian / Ubuntu:

   # service apache2 reload

   For CentOS / RedHat / CloudLinux:

   # service httpd reload