This is a generic error that happens when there is an issue with your HRS setup in myallocator. It can mean several things.
One of the possible causes of this error is wrong Cancellation Fee set up. According to German laws, the maximum allowed cancellation fee is 90%
Please, go to you Channels -> HRS -> Channel-specific Options (last page) and make the necessary changes to the Cancellation Fee rate.
Afterwards, please go to Availability page and send a Full Refresh to the HRS Channel to re-establish the connection.
If the problem still occurs, please submit a ticket to our Support Team in order for us to investigate.