I have a 10+ years old project with lots of modules - several war, GWT and regular jar modules. All strung together with Maven. It has always worked, and works in 2020.3 as well.
After upgrading to 2021, it is pretty messed up. First: everything builds in maven from the command prompt, i can run in Tomcat.
In intellij, though, it suddenly can't find libraries. If i go in to module settings, libraries that exist are red, even though it's in the location in my repo.
Those errors can sometimes be fixed by "reimporting". But when i open intellij again, it's messed up again.
Furthermore, i cannot run my project within intellij/jetty anymore. When i try to run, it complains about not finding basic classes like HttpServletResponse, "cannot access javax.servlet.Filter".
Another thing that i think i have another ticket for, is that when i start intellij, and try to run my war, it says "no GWT module found". If i then again "reimport", it finds the module again...(until if i build with mvc from the command prompt, after which no gwt module can be found again)
These things make 2021.1 unusable for me. I'm not sure what i can do, given that i can build the project outside intellij, and it works prior to 2021.1. I have downgraded to 2020.3 to be able to work.