Created attachment 35632 [details] demo WAR that generates StackOverflowError upon invocation of index.jsp A tagfile that contains recursive invocation of itself cannot be compiled under Tomcat 9.0.2. Works OK works OK in 8.5.24. Sample WAR attached. Invoking /recursive-taglib/index.jsp causes java.lang.StackOverflowError.
Thanks for the test case. Although it could need to be further reviewed, I think a change to what prototype mode did was not right. The fix will be in 9.0.3.