Groovy failures after upgrading eclipse

Question

Recently upgraded to Eclipse 2020-12 (4.18.0) and Groovy hasn't worked since.

Upgraded Groovy with no improvement.

Now running (expanding all the "What's installed" tree)

• Eclipse Groovy Development Tools org.codehaus.groovy.eclipse.feature.feature.group
• Groovy Compiler 2.5 org.codehaus.groovy25.feature.feature.group
• Groovy-Eclipse Compilerless feature org.codehaus.groovy.compilerless.feature.feature.group
• Groovy-Eclipse Headless feature org.codehaus.groovy.headless.feature.feature.group
• Eclipse JDT Core patch for Groovy org.codehaus.groovy.jdt.patch.feature.group
• Groovy Compiler 3.0 org.codehaus.groovy30.feature.feature.group

All with version 4.0.0.v202012311505-e2009-RELEASE. However, the entry for "Eclipse JDT Core patch for Groovy" has a red '+' overlaid on its plugin icon.

Referring to the Eclipse log, java.lang.NoClassDefFoundError: org/codehaus/jdt/groovy/integration/LanguageSupport is being reported constantly. I'm assuming the patched JDT Core is not installed correctly but not sure what to do next.

Answer 1

For me I couldn't open groovy files, all I got was a blank editor pane. Initially I installed groovye-eclipse from eclipse market place.

@emilles comment was spot on. I did have an incorrect version installed. After uninstalling and adding new update site specific to my eclipse version (2020-12) it works fine. I can open and edit groovy files.