400 Logout Error after Upgrade from 19.0.2 to 21.0.2

Hello,

I’m connecting different SAP Cloud Applications to our keycloak. Recently I performed an upgrade from keycloak 19.0.2. to 21.0.2. Most applications work fine (also the logout), but the SAP IAS logout isn’t working as excepted.

In SAML trace I receive a 400 - Bad Request error, no logout is performed and the session is still active. I had contact to the SAP support team, they couldn’t find an error.
When I performed a downgrade to 19.0.2. everything is working fine again.

Is this a know issue / behaviour? Does anyone know how I can solve it?

Thank you for your help.