GhidraDev can't find supported JDK

[goatshriek]

Does anyone know what criteria GhidraDev (the Eclipse plugin) uses to find the JDK? With Ghidra 11.3, I am unable to link my project to Ghidra, with the error message saying "A supported JDK is not associated with this Ghidra installation. Please run this Ghidra and try again."

I'm on a Windows 11 machine, using Microsoft JDK 21.0.6. So far I have:

• Completely re-installed Eclipse
• Made sure that the only JDK on my system is 21, and updated it to the latest patch level
• Run Ghidra's support/ghidraClean script (losing all of my configs in the process, unfortunately)
• Removed all Eclipse metadata on the project and the workspace

And yet the issue persists. Ghidra itself starts fine, with the splash screen listing the JDK that I have installed. I saw #6215, but it simply mentioned installing a JDK, which I already have. I was using this JDK fine for older versions, so I'm not sure where this issue came from.

[d-millar]

If you execute "javac --version", do you get "javac 21.0.6"?

[ryanmkurtz]

It looks for the Ghidra installation's user settings directory...there should be a java_home.save file in there.

[ryanmkurtz]

Also, are you overriding the user settings directory with changes to launch.properties or XDG env vars?

[ryanmkurtz]

Also, are you using the latest GhidraDev plugin?

[goatshriek]

javac --version does indeed give me javac 21.0.6, and checking the location with where points me back to the binary in the JDK.

I can't find a java_home.save file, at least not alongside the preferences, logs, and other stuff near the preferences in %APPDATA%\ghidra\ghidra_11.3_PUBLIC. I tried running a script within Ghidra to see if it would generate one as a byproduct of compiling the script, but no such luck.

However, I was able to get it to progress by executing echo %JAVA_HOME% > %APPDATA%\ghidra\ghidra_11.3_PUBLIC\java_home.save, after which it worked (though it yelled at me about PyDev despite me not having it installed).

The version GhidraDev reports is 5.0.202501081224. I'm assuming it's the most up to date as it was installed by Ghidra 11.3. At least, that's what I'm assuming happened after I blew away my Eclipse install and re-did my Eclipse integrations with the new install.

I haven't purposefully modified launch.properties or any XDG stuff (can you do that on Windows?), so I don't think that's happening?

[ryanmkurtz]

Would you mind trying to delete your handmade java_home.save file, and unsetting your JAVA_HOME env, and trying again? Ghidra using JAVA_HOME is new for 11.3 and I'm wondering if when set, the java_home.save file isn't getting written for some reason.

[ryanmkurtz]

Actually I see that a set JAVA_HOME is indeed preventing Ghidra from writing java_home.save. I will get it fixed tomorrow for an upcoming patch release.

[goatshriek]

Ah, that worked as well. I removed the project, it's metadata, and the java_home.save file, changed JAVA_HOME to JAVA_HOME_OLD, and then when I launched Ghidra 11.3 it created the java_home.save file in the preferences. After that GhidraDev allowed me to link the project after re-importing it.