@matthias1 that sounds strange.

The stack trace you have posted may be a bug in atlassian-connect-spring-boot 2.2.2. But if you are h the ErrorController, it means your app has thrown an exception somewhere else, and Spring Boot is trying to serialize a response for it. Have you found what the original error was?

Have you upgraded to Spring Boot 2.5, the latest minor version? atlassian-connect-spring-boot 2.2.2 may require running against Spring Boot 2.5. Our test suite runs fine against Spring Boot 2.4.5, but there may be a corner case here that we don’t have covered.