How to fix “Http11NioProtocol: Error reading request, ignored”

Question

My spring-boot application fails after start with an NPE in the tomcat server when running on azure kubernetes service with SSL.

First, what does work successfully:

Answer 1

That is a known bug in Apache Tomcat 9.0.24. It is triggered by sending plain text to an TLS enabled connector. It is safe to ignore but since it is rather noisy you probably want to upgrade to the recently released 9.0.26 where this has been fixed.