Plesk Installer reports the warning: Found one or more domains with mixed case names

Symptoms

Plesk Installer reports the following warning:

CONFIG_TEXT: WARNING: Found one or more domains with mixed-case names. Such domains may have trouble working with the "FPM application server by Apache" handler.
29 Example.com Example.com

Cause

Product issue:

• #PPP-31339. "Domains with upper case letters may lead to a Plesk bug with ID PPP-31339"
  Fixed in:
  • Plesk Obsidian 26 April 2018.

Resolution

Workaround

If update is not possible for some reason you may try the following:

In Domains > Example.com > Hosting Settings rename Example.com to Example.com.old and then do it once again to example.com

Note: In some cases, after changing all uppercase letters to lowercase letters in domain names, the warning about mixed case names may still showing. In this case, the warning can be ignored.