I was reading this post (https://www.baeldung.com/openfeign-http-patch-request) because I had exactly the same problem, but it is important to mention the correct version of feign-okhttp, because when I used 13.3 ( that intellij generates for me) it didn't work, and kept returning the Invalid HTTP method: PATCH executing PATCH error, but when changing to version 13.2.1 it ran
I was reading this post (https://www.baeldung.com/openfeign-http-patch-request) because I had exactly the same problem, but it is important to mention the correct version of feign-okhttp, because when I used 13.3 ( that intellij generates for me) it didn't work, and kept returning the Invalid HTTP method: PATCH executing PATCH error, but when changing to version 13.2.1 it ran