Web.xml: accordingly to servlet specification, famous section 11 (Mapping Requests to Servlets) there are a number of rules of resolving <servlet-mapping>/<url-pattern> value. Currently IDEA provides no inspection to check it. It can be provided. Some clarification after playing with Tomcat and SAS: 1. An URL pattern with several asterisks is used for exact match only, probably should cause a warning in web.xml editor. I.e. <url-pattern>/a*/*</url-pattern> does not match /abc/myurl. It will match only URL "/a*/*". 2. The same with the single asterisk which is not the first and not the last character in url-pattern. 3. An URL pattern which starts with asterisk should be the extension mask (e.g. no slashes). I.e. <url-pattern>*.jspf-test</url-pattern> matches /b/bb/case-b.jsp-test. 4. An URL pattern should start with slash or asterisk. SAS reports error for <url-pattern>a/case-a</url-pattern>, but Ok for <url-pattern>/a/case-a</url-pattern>.