Errors in /var/log/modsec_audit.log: collections_remove_stale: Failed to access DBM file "/var/awp/data/msa/apache-global": Permission denied

Symptoms

1. Atomic Basic ModSecurity ruleset is enabled at Tools & Settings > Web Application Firewall (ModSecurity) 
2. Error in /var/log/modsec_audit.log :

   CONFIG_TEXT: --b8876e6d-H-- Message: collections_remove_stale: Failed to access DBM file "/var/awp/data/msa/apache-global": Permission denied
   Stopwatch: 1494012668966140
   Stopwatch2: 1494012668966140 3289; combined=1756, p1=90, p2=1487, p3=20, p4=49, p5=62, sr=7, sw=0, l=0, gc=48
   ModSecurity for Apache/2.9.0 (http://www.modsecurity.org/); 201705041602.
   Server: Apache
   Engine-Mode: "ENABLED"

Cause

This is Plesk bug with ID #PPPM-6202 which will be fixed in future updates.

Resolution

As a workaround, log in to Plesk server via SSH and change the permissions:

# chown www-data.www-data /var/awp/data/msa/
# chown www-data.www-data /var/awp/data/audit
# chown www-data.www-data /var/awp/data/suspicious
# chmod o-rx -R /var/awp/data/*
# chmod ug+rwx -R /var/awp/data/*

Note: the commands above are for Ubuntu/Debian installations. For RedHat/CentOS/Almalinux/Rockylinux, replace 'www-data' username with 'apache'

If the issue persists, turn off the affected rule by the rule's ID in Plesk.