Dear GeoNet Community, good day
We have a strange problem, 2 days passed, no any hint to solution yet.
The interesting thing is that this question have already been asked, but no answer was given (at least, if there is an answer, it isn't helpful in my case):
https://community.esri.com/thread/176861
We have installed GeoEvent Server following the Arcgis documentation. When we try to open GeoEvent Manager, we get the following:

Trying to see what's going on:

And truthfully, it seems to us, that the reason is in the last error ( owningSystemUrl ). And we have no idea how we can fix it.
Will be appreciated for any help. Please, share your knowledge if you've had something like this or have any assumptions.
Kind regards,
Ilia