Can't download large files from a Plesk site: ap_pass_brigade failed in handle_request_ipc function

Symptoms

• Can't download large files from a website in Plesk, or the download speed is slow

• Proxy mode is enabled in Domains > example.com > Hosting & DNS > Apache & nginx

• PHP handler set to FastCGI application server by Apache in Domains > example.com > PHP

• Records like these are logged to /var/www/vhosts/example.com/logs/error_log

  [fcgid:warn] [pid 13949] (104)Connection reset by peer: [client 203.0.113.2:43210] mod_fcgid: error reading data from FastCGI server, referer: https://example.com/index.php
  [fcgid:warn] [pid 13949] (104)Connection reset by peer: [client 203.0.113.2:43210] mod_fcgid: ap_pass_brigade failed in handle_request_ipc function, referer: https://example.com/index.php

Cause

Insufficient FastCGI limits.

Resolution

1. Log in to Plesk

2. Go to Domains > example.com > PHP.

3. Increase the max_execution_time value.

4. Go to Domains > example.com > Hosting & DNS > Apache & nginx.

5. Add the following directives under Additional directives for HTTP & Additional directives for HTTPS:

   <IfModule mod_fcgid.c>
   FcgidMaxRequestsPerProcess 500
   FcgidBusyTimeout 3600
   FcgidMaxRequestLen 1073741824
   FcgidProcessLifeTime 7200
   </IfModule>