Mysterious Eclipse JSP Validation Errors

Question

Eclipse (Helios) occasionally marks valid looking JSP content as having errors. It seems like it often breaks when I use the tag. For example, in a JSP with just th

Answer 1

Try to check your project classpath. It looks like you don't have the JSP library in your project (hence the "JspException cannot be resolved"), or that your library version isn't the same as the JSP compiler version.

The library is included by default in the application server on which you deploy your app, so the code runs perfectly when deployed. However, if the Eclipse internal compiler is missing a library (or have an incorrect version), the Eclipse editor shows you error that doesn't exists in app server.