Cannot Execute Tests in Eclipse 2019-03

Steffi S. :

I've got a fairly vanilla Eclipse 2019-03 RCP&RAP installation (just added Tycho and a couple Maven connectors), yet when I start a standard JUnit test, I get the following exception

java.lang.AbstractMethodError: org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests([Ljava/lang/Class;Ljava/lang/String;[Ljava/lang/String;[Ljava/lang/String;[[Ljava/lang/String;Ljava/lang/String;Lorg/eclipse/jdt/internal/junit/runner/RemoteTestRunner;)[Lorg/eclipse/jdt/internal/junit/runner/ITestReference;
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:525)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)

Another workspace with the same Eclipse installation simply brings the error message:

No JUnit tests found.

No tests found with test runner 'JUnit 4'.

For me it's reproducible (for a brand new unit test), but on other machines with similar builds the same setup will suddenly start working.

The library "JUnit" I added via the build path points to JUnit 4.12 and Hamcrest 1.3.0, which I think is correct.

I found bug 526144, but it's supposed to be resolved.

Plug-in JUnit tests don't work either, but that seems to be an entirely different problem.

What can I do to get JUnit to work with Eclipse?

Steffi S. :

The only think that helped was to install the newest Eclipse 2019-06:

https://www.eclipse.org/downloads/packages/release/2019-06/r