Eclipse - JUnit - An internal error occurred during: "Launching MyMavenModule". NullPointerException

Question

I recently upgraded to Eclipse 2020-06. After the upgrade, I'm now unable to run Junit tests in Eclipse while they run smoothly in Maven.

Here is a screenshot of the error :

I tried to delete the .metadata folder (I made a backup before), start a fresh copy of eclipse and import my project in it and event start another fresh copy of eclipse and create a simple JUnit test in it.

All these attempts result in the same error.

What am I doing wrong?

EDIT:

Answer 1

I wasn't able to fix the problem. I tried to install Java Development Tool but the installer failed with an OutOfMemoryException.

So I re-download Eclipse 2020-06 manually, I re-install all my plugins and re-import my projects.

My guess is the ooomph installer messed around somehow during the upgrade from Eclipse 2020-03 to Eclipse 2020-06.

I lost nearly a day to fix this !

Answer 2

According to the screenshot you did not have Eclipse 2020-06 (4.16.0), but a kind of beta/preview version which might be unstable:

eclipse.buildId=4.16.0.I20200604-0540 means integration build (I) of June 4, 2020 (20200604) at 5:40 (0540). After this build and before the release there were a couple of integration builds and one release candidate. It was the second release candidate, one week later, which became the Eclipse 2020-06 release and which was released on June 17, 2020.

If you do not want to have an integration build, make sure that in Window > Preferences: Update/Install > Available Software Sites you don't have an update site with a URL that contains staging.