ResolutionDebug logging is not enabled for Customer & Business Manager by default.
If an error occurs, the debug logging helps you collect the information necessary for our support engineers to diagnose and fix it. You should turn this service on, reproduce the error, and attach the newly added log records to the error description.
To turn on the debug logging, do the following:
1. In the file config.php, set "true" for the parameter ALLOW_DEBUG_LOGGING.
If you run Linux, the file resides in /opt/plesk-billing/lib/lib-billing/include/config/.
If you run Windows, the file resides in the directory %plesk_dir%\billing\htdocs\lib-billing\include\config\.
2. Go to Server Administration Panel -> All Settings -> Debug Log and click Enable Logging in the opened page.
This information can be found in Parallels Customer and Business Manager Administrator's Guide and also at the Parallels Plesk Panel documentation page.