Tycho generates "Unknown OSGi execution environment: 'JavaSE-20'" error upon Maven 'clean install' command

[StephenF55]

Hi,
I get the above error when I try to perform the "Build the language" step (step 2) of the procedure. That is running "mvn clean install" from my 'git\maven-xtext-example' directory. The exact errors produced are:

[ERROR] Internal error: org.eclipse.tycho.core.ee.UnknownEnvironmentException: Unknown OSGi execution environment: 'JavaSE-20' -> [Help 1]
org.apache.maven.InternalErrorException: Internal error: org.eclipse.tycho.core.ee.UnknownEnvironmentException: Unknown OSGi execution environment: 'JavaSE-20'
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:109)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:910)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:104)
at java.lang.reflect.Method.invoke (Method.java:578)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:283)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:226)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:407)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:348)
Caused by: org.eclipse.tycho.core.ee.UnknownEnvironmentException: Unknown OSGi execution environment: 'JavaSE-20'
at org.eclipse.tycho.core.ee.ExecutionEnvironmentUtils.getExecutionEnvironment (ExecutionEnvironmentUtils.java:96)
at org.eclipse.tycho.core.osgitools.OsgiBundleProject.applyBestOfCurrentOrConfiguredProfile (OsgiBundleProject.java:778)
at org.eclipse.tycho.core.osgitools.OsgiBundleProject.readExecutionEnvironmentConfiguration (OsgiBundleProject.java:748)
at org.eclipse.tycho.core.resolver.DefaultTychoResolver.setupProject (DefaultTychoResolver.java:103)
at org.eclipse.tycho.core.maven.TychoMavenLifecycleParticipant.afterProjectsRead (TychoMavenLifecycleParticipant.java:111)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:223)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:910)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:104)
at java.lang.reflect.Method.invoke (Method.java:578)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:283)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:226)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:407)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:348)
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/InternalErrorException

Please note that the preceding "Increase memory" step 1 did NOT work for me, as when I try the command (or at least the equivalent windows - I am using Windows 11 machine - to the Unix one) given, the subsequent 'clean install' generates the following error:

C:\Users\Alison\git\maven-xtext-example>set MAVEN_OPTS="-Xmx512m -XX:MaxPermSize=256m"

C:\Users\Alison\git\maven-xtext-example>mvn clean install
Invalid maximum heap size: -Xmx512m -XX:MaxPermSize=256m
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

[cdietrich]

Xtext has no offical java 20 support. also dont know if the mavern or tycho version you use has
MaxPermSize needs to be removed

[cdietrich]

see also https://github.com/xtext/maven-xtext-example/blob/master/.github/workflows/build.yml

[StephenF55]

Hi Christian, Many thanks for replying so promptly.

I'd like to align my environment, so please can you advise what Maven and Tycho versions you use? Note that I have Maven v3.9.2 installed, whilst Tycho is v2.7.5 (per the parent pom definition)

[cdietrich]

this both should work,
question is what java version you use. should be 17

[StephenF55]

Thanks for confirming Maven & Tycho.
Ok, I'll try 17 instead of 20

[StephenF55]

Thank you very much Christian, switching Java from '20' to '17' fixed the problem. Maven clean install now builds fine in the command line.

However, rather frustratingly, I am still seeing the attached 4 errors and multiple hundred warnings in Eclipse. Do you have any suggestions what the problem might be? Note that the Eclipse version I'm running is:

Eclipse DSL Tools (includes Incubating components)
Version: 2023-03 (4.27.0)
Build id: 20230309-1520

eclipse errors & warnings@24_07_23.xlsx

[cdietrich]

examples should be imported in runtime project only
the discouraged access and deprecated warnings are expected.

[StephenF55]

Understood. Thanks again for your help Christian, much appreciated.