The following error messages appear in Plesk at Domains > example.com > Logs or in domain's error log file
AH01068: Got bogus version 111, referer: (22)Invalid argument: AH01075: Error dispatching request to :, referer:
This is Apache bug 49671, which has been fixed in Apache version 2.4.16.
Note: Apache 2.4.16 is not available in default repositories of CentOS/RHEL 7.x.
These error messages can be safely ignored - there are no consequences for the website.
To get rid of these messages, you may switch the website to nginx only.