PM is installed on Windows 11 and works (after skipping this error) as expected.
When I start PM, the following message is issued:

loading extension
Pegasus Mail has encountered an operating
system error while attempting to load the
extension ,MiniDump‘. The error code returned by
Windows was: "The specified module could not
be found.

I just click away the message and PM works as intended.

Where can i find this module and where must it be placed?

Thank you for your help.

If you installed Pegasus Mail on Windows 11 and then copied you mailbox from another installation, then you had the MiniDump extension installed on the previous machine or OS that is not installed on the current one. For now, use a file explorer to navigate to your mailbox directory then find and delete the file named MiniDump.fff. It will be recreated with an installation of the MiniDump extension.

Post back if you did not copy the mailbox, or \PMAIL from a different machine as this would indicate a MiniDump installation that is not working and requires further removal

Thank You, Brian, that helped! It's all OK now.