[keycloak-user] HTTP status 400 from Tomcat after successful login

Hello everyone, I have configured a web application, that is running in Tomcat, to authenticate users with Keycloak. Everything is running fine if I deploy the app to my local Tomcat, even when using the remote Keycloak instance. However, when I deploy the app to another Tomcat running behind an Apache HTTP Server, the following happens: * When I navigate to https://my-domain.tld/app I get redirected to the Keycloak login * After I log in successfully, Keycloak redirects me to <IP>:<PORT>/app of the Tomcat * The Tomcat answers with HTTP status 400 My keycloak.json looks like this: { "realm": "cdb_test", "auth-server-url": "https://keycloak-server.tld/auth", "ssl-required": "external", "resource": "cdb_test", "public-client": true } The VHost is configured like this: ProxyPass /app http://<IP>:<PORT>/app/ ProxyPassReverse /app http://<IP>:<PORT>/app/ ProxyPassReverseCookiePath / /app/ I turned on debug logging for the Keycloak Tomcat adapter, see attachment. Any advice? Thanks in advance Timo