Article ID: 124376, created on Feb 4, 2015, last review on Aug 22, 2016

  • Applies to:
  • Plesk 12.5 for Linux
  • Plesk 12.0 for Linux
  • Plesk 11.5 for Linux


  • Plan cannot be synchronized between CBM and Plesk. When Sync in Business Setup > Plans is selected the following error message appears:

    Error: Sync errors:
    Failed to repair the plan in panel 'Local Parallels Plesk Panel server (': Failed to perform the request to the panel by the URL 'https://localhost:8443': <html>
    <head><title>502 Bad Gateway</title></head>
    <body bgcolor="white">
    <center><h1>502 Bad Gateway</h1></center>
    <br/>Check the panel, network, and firewall settings and try again.
    Please resolve the problems manually and retry to sync this plan. 
  • WHMCS cannot communicate with Plesk. If go to WHMCS > Setup > product and services > Servers, click on Edit option and click on "Test connection" if returns FAILED.

    The following error is shown in Module log in WHMCS.

    <head><title>502 Bad Gateway</title></head>
    <body bgcolor="white">
    <center><h1>502 Bad Gateway</h1></center>
  • '/var/log/syslog' or '/var/log/messages' contains the following string:

    kernel: grsec: From denied ptrace of /usr/sbin/sw-engine-fpm(sw-engine-fpm:8880) by /usr/sbin/sw-engine-fpm[sw-engine-fpm:8881] uid/euid:1000/1000 gid/egid:1000/1000, parent /usr/sbin/sw-engine-fpm[sw-engine-fpm:8880] uid/euid:1000/1000 gid/egid:1000/1000
  • Execution of the following command returns the same result:

    # sysctl kernel.grsecurity.harden_ptrace
    kernel.grsecurity.harden_ptrace = 1


Linux kernel security ptrace protection is enabled.


Disable ptrace protection

# echo "kernel.grsecurity.harden_ptrace = 0" >> /etc/sysctl.conf

# sysctl -p

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