Every time I build a maven project and turn it into a web project, there are always so many files here, and there will also be a red cross of error pages, which is very uncomfortable. Although there was no error in the project, it was always an error message for me. So I looked for a long time, and finally found the cause of the problem.

It turns out that this is a problem of eclipse itself. If you change to a web project, you will add web.xml , but the compiler will not update itself and will report this error. So you can cut it web.xml Save all the information in Ctrl + s, then the compiler will refresh, and then you are putting the clipped content back web.xml Finally, the problem is solved.