axbu,
I’m afraid that error doesn’t really tell us much. There would be more info in the Error log perhaps with exactly what the failure is.
I suspect the issue could be around an inability to find required software, could you try these steps to see if it resolves the issue?
1) Go to Preferences > Install / Update > Available Software Sites
2) Click Add and add this URL https://download.eclipse.org/releases/2024-03/
– give it a suitable name and ensure it is checked in the list of sites.
3) Now attempt to install Copilot4Eclipse from the marketplace.
If this fails, please look for the option in the dialog that would display the “original error” and reply with that so we can debug further.
Do let us know if you’re able to install the plugin after these steps.