Consider:
When I create a simple Maven project in Eclipse I am getting this error:
web.xml is missing and
I had the same problem, even though I had 'src/main/webapp/WEB-INF/' folder with correct web.xml.
The problem disappeared after I recreated (maven->eclipse) configuration with
Maven build.. I executed mvn eclipse:clean eclipse:eclipse
And then I used Maven -> Update Project to add (eclipse->maven) plugin specific options.