Update:
Solution was found
Apply regional settings to the Local System account (Windows 10)
https://www.perennitysoft.com/support/kb/faq.php?id=86
This post can be deleted - sorry for any inconvinience
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HostMonitor 12.98
After fresh Windows 10 installation:
When I start hostmon.exe interactively, the logfile is created as "Friday-log.txt"
When started as service (Local System), the logfile is created as "Freitag-log.txt" (so as German Language)
LogsMan started via RCC doesn't find that file, because it's looking for the english file name.
Windows 10 system where Hostmonitor is installed was installed in German initially and I've changed to English language for my user account.
Goal would be to make service running in English and create "Friday-log.txt"