An internal error occurred during: "Updating Maven Project". Unsupported IClasspathEntry kind=4

Question

As the title mentioned I have the following problem: I use Eclipse with Maven Nature and when I update my Maven Project, I get this error:

An internal error occurred during: "Updating Maven Project".
Unsupported IClasspathEntry kind=4

The solution that always comes back is the following:

• rightclick project, remove maven nature
• mvn eclipse:clean (with project open in eclipse/STS)
• (sometimes they suggest to do mvn eclipse:eclipse next)
• rightclick project and reenable maven nature

Now I exhaustively tried all combinations several times. But I always keep getting the above error. The error starting occurring when I had to mvn eclipse:eclipse the project. Before it was always running fine using only m2eclipse features and setting everything in eclipse.

Answer 1

I had to do it slightly different to work for me:

1. rightclick project, remove maven nature (or in newer eclipse, "Maven->Disable Maven Nature")
2. mvn eclipse:clean (with project open in eclipse/STS)
3. delete the project in eclipse (but do not delete the sources)
4. Import existing Maven project