Test connection always ends with "API Error:Decryption of SNMPv3 password failed."

**CMK version:**2.2.0p24
**OS version:**Appliance 1.6.8

Error message: API Error:Decryption of SNMPv3 password failed.

Hello,
I get this error message every time when I run it with a new snmp host connection test. It appears directly on all check windows, so I guess it is an internal checkmk error. I tried differnet passwords but it does’nt change anything.
The error also appears when I run the test on working snmp hosts I added some time ago. So I guess there was a change in one of the last updates that causes this problem.

You might want to get started by telling folks, how your hosts are configured exactly.
Just posting the error probably does not enable anyone to help.