I tried to do a spike to switch the (large) IntelliJ build-based* Groovy project I am working on to from Groovy 2.5.10 to the current Groovy 3 release (3.0.7) today, but immediately got a "Groovyc: Internal groovyc error: code 1" that (contrary to previous times I encountered that error) did not go away through a rebuild of the current module or the whole project.

The same problem then occurred with the current Groovy 2.5 release (2.5.14).

I have now created a minimal IntelliJ Groovy project, that contains a single test that outputs the Groovy version - and to my surprise this still gives "Groovyc: Internal groovyc error: code 1" in the 'Builder "Groovy stub generator" requested rebuild of module chunk "GroovyMinimal"' phase...
The minimal project builds & runs without problems when switching back to Groovy 2.5.10.

My complete build environment is:
IntellliJ 2020.2.3
AdoptOpenJDK jdk- (same behavior when using
Windows 10 Pro 64-bit (build 19041.804)
Groovy 2.5.10 (works) / 2.5.14 (fails) / 3.0.7 (fails) respectively
(Hardware: Intel i5 CPU, 32GB RAM, 2TB SSD)

The project consists only of the (non-global) respective Groovy library dependency, and the following Groovy test file (for simplicity I use the JUnit that comes with this particular IntelliJ version in the minimal project):

package minimal.groovy

import org.junit.Ignore
import org.junit.Test

class MinimalTest {
 void test() {
  println "Grooovy: ${GroovySystem.version}"

Is this a known problem ? If not, feedback from other Groovy users would be appreciated. I am evidently trying to find a solution to this problem, but also to discern the extent of it: E.g. does it also occur when using Maven or Gradle as a build system (which would surprise me, since that is what most people use) ? If your build works fine with Groovy 2.5.14 / 3.0.7, what is your build environment ?

Thanks, cheers,

*Since the question typically pops up: The environment I work in does not allow access to build repositories on the internet, and it is not possible to automatically mirror repositories locally, and we have no complicated build steps, so using Gradle (or Maven) would have no real advantage for us, so we use the build system that is best integrated with our IDE and has good (apart from some minor hickups) minimal rebuild support, etc, i.e. an IntelliJ build.