I have read the Grails 4.X documentation that doesn't seem to indicate the versions of Java that it would work with, except to say it no longer works with java 7.

Before installing Grails 4.0.3 you will need as a minimum a Java Development Kit (JDK) installed version 1.8 or above.

-- http://docs.grails.org/latest/guide/gettingStarted.html

I am running with 14.0.1+7 installed on my mac using sdk-man. When I try to build an existing grails project, or create a new project, it fails with an error.

Steps to reproduce:

1. Install jdk 14 using sdk-man sdk install java 14.0.1-open

2. Install Grails sdk install grails 4.0.3

3. Create Grails project grails create-app MyApp

4. Results

$ grails create-app testJDK14
java.lang.NoClassDefFoundError: Could not initialize class org.codehaus.groovy.vmplugin.v7.Java7
        at org.codehaus.groovy.vmplugin.VMPluginFactory.<clinit>(VMPluginFactory.java:43)
        at org.codehaus.groovy.reflection.GroovyClassValueFactory.<clinit>(GroovyClassValueFactory.java:35)
        at org.codehaus.groovy.reflection.ClassInfo.<clinit>(ClassInfo.java:107)
        at org.codehaus.groovy.reflection.ReflectionCache.getCachedClass(ReflectionCache.java:95)
        at org.codehaus.groovy.reflection.ReflectionCache.<clinit>(ReflectionCache.java:39)
        at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.registerMethods(MetaClassRegistryImpl.java:209)
        at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.<init>(MetaClassRegistryImpl.java:107)
        at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.<init>(MetaClassRegistryImpl.java:85)
        at groovy.lang.GroovySystem.<clinit>(GroovySystem.java:36)
        at org.codehaus.groovy.runtime.InvokerHelper.<clinit>(InvokerHelper.java:86)
        at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.bitwiseNegate(ScriptBytecodeAdapter.java:842)
        at org.grails.config.NavigableMap.<clinit>(NavigableMap.groovy)
        at org.grails.cli.GrailsCli.<clinit>(GrailsCli.groovy:77)
Exception in thread "main" java.lang.NoClassDefFoundError: Could not initialize class org.codehaus.groovy.reflection.ReflectionCache
        at org.codehaus.groovy.runtime.dgmimpl.NumberNumberMetaMethod.<clinit>(NumberNumberMetaMethod.java:33)
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
        at java.base/java.lang.reflect.ReflectAccess.newInstance(ReflectAccess.java:124)
        at java.base/jdk.internal.reflect.ReflectionFactory.newInstance(ReflectionFactory.java:346)
        at java.base/java.lang.Class.newInstance(Class.java:604)
        at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.createMetaMethodFromClass(MetaClassRegistryImpl.java:257)
        at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.<init>(MetaClassRegistryImpl.java:110)
        at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.<init>(MetaClassRegistryImpl.java:85)
        at groovy.lang.GroovySystem.<clinit>(GroovySystem.java:36)
        at org.codehaus.groovy.runtime.InvokerHelper.<clinit>(InvokerHelper.java:86)
        at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.bitwiseNegate(ScriptBytecodeAdapter.java:842)
        at org.grails.config.NavigableMap.<clinit>(NavigableMap.groovy)
        at org.grails.cli.GrailsCli.<clinit>(GrailsCli.groovy:77)

I found a related issue with jdk 14 and gradle 5.1.1 that Grails ships with that recommends upgrading gradle to 6.3+. It was not specific to Grails.

So I upgraded gradle in my Grails project using the gradle-wrapper.properties file, but still receive the same, although that cleared it for many using Gradle, but not Grails.

Is there a list of JDKs that is known to work with Grails 4.X?