[keycloak-user] CORS

Hello, I have a front-end and one back-end application. For the front-end I entered the web origin: http://localhost:4000. Additionally I added a line <enable-cors>true</enable-cors> to the standalone.xml (wildfly 10 / keycloak 1.9.4.Final) The browser console displays: The 'Access-Control-Allow-Origin' header contains multiple values 'http://localhost:4000, http://localhost:4000';, but only one is allowed. Origin 'http://localhost:4000' is therefore not allowed access. If I remove the line from the client I get: localhost/:1 XMLHttpRequest cannot load http://localhost:8080/auth/realms/... /protocol/openid-connect/token. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4000' is therefore not allowed access. Has anyone a hint what could cause this? Thx a lot Kevin