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Some websites are unavailable: "mod_fcgid: can't apply process slot for /var/www/cgi-bin/cgi_wrapper/cgi_wrapper"

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Pavel Mikhaylov
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Applicable to:

  • Plesk for Linux

Symptoms

  • One or several websites / webmail interfaces load continuously and eventually fail with one of the following errors in a browser:

    PLESK_INFO: 500 Internal Server

    OR

    PLESK_INFO: 503 Service Temporarily Unavailable

    OR

    PLESK_INFO: 502 Bad Gateway

    OR

    PLESK_INFO: 504 Gateway Time-out

  • Some websites are loading very slow.

  • In the domain error logfile /var/www/vhosts/system/example.com/logs/error_log the following message can be found:

    CONFIG_TEXT: [warn] [client 203.0.113.2] mod_fcgid: can't apply process slot for /var/www/cgi-bin/cgi_wrapper/cgi_wrapper

  • In the domain error logfile /var/www/vhosts/system/example.com/logs/proxy_error_log the following error message can be found:

    CONFIG_TEXT: [log_config:warn] [pid 30019] (32)Broken pipe: [client 203.0.113.2:51022] AH00646: Error writing to |/opt/psa/admin/sbin/pipelog 7081, referer: http://www.example.com/

Cause

The FcgidMaxProcesses limit has been reached.

OR

Client closed the connection before waiting for the server to respond.

Resolution

If the client closed the connection before receiving server's response, the issue is on the client side. Nothing to do on the server.

To increase FcgidMaxProcesses:

  1. Connect to a Plesk server via SSH.

  2. Increase the value of FcgidMaxProcesses:

    2.1. Open the file fcgid.conf in any text editor. Location of the file is:

    • on CentOS/RHEL-based OS: /etc/httpd/conf.d/fcgid.conf

    • on Debian/Ubuntu-based OS: /etc/apache2/mods-enabled/fcgid.conf

    2.2. Navigate to the directive FcgidMaxProcesses and increase the value.

    2.3. Save the changes and close the file.

  3. Check if there are other files in the Apache configuration directory that can override parameters in fcgid.conf:

    • for CentOS/RHEL-based distributions:

      # grep -ir 'FcgidMaxProcesses' /etc/httpd/conf.d/

    • for Debian/Ubuntu-based distributions:

      # grep -ir 'FcgidMaxProcesses' /etc/apache2/

      Note: If files are found, increase the FcgidMaxProcesses limit in these files too.

  4. Restart the Apache service:

    • for CentOS/RHEL-based distributions:

      # service httpd restart

    • for Debian/Ubuntu-based distributions:

      # service apache2 restart

  5. If the same issue still occurs, increase the limit of FcgidMaxProcesses to a greater value (up to 1200) and restart Apache.

  6. If the solution above did not help, try to use nginx+PHP-FPM combination:

    1. Run PHP as FPM application served by nginx at Plesk > Domains > example.com > PHP Settings.

    2. Enable the options below at Plesk > Domains > example.com > Apache & nginx Settings:

      • Proxy mode

      • Smart static files processing

      • Serve static files directly by nginx

Comments

2 comments

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    TechTown GmbH

    did you tested that solution...??

    after the restart of the apache the value changes back to the original value

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  • Avatar
    Artyom Baranov

    @TechTown GmbH

    Hello! I have just tested the solution on my Plesk Onyx (CentOS 7)

    # grep -iR 'FcgidMaxProcesses' /etc/httpd/
    /etc/httpd/conf.d/fcgid.conf: FcgidMaxProcesses 20   <----------------before changing

    # vi /etc/httpd/conf.d/fcgid.conf
    # grep -iR 'FcgidMaxProcesses' /etc/httpd/
    /etc/httpd/conf.d/fcgid.conf: FcgidMaxProcesses 40   <----------------after changing

    # service httpd restart

    # grep -iR 'FcgidMaxProcesses' /etc/httpd/
    /etc/httpd/conf.d/fcgid.conf: FcgidMaxProcesses 40   <----------------after Apache restart

    Please describe a scenario when this setting was changed to original value.

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