How to debug start of eclipse plugin?

Question

I try to migrate an eclipse plugin from Java8 to Java9. If I start a debug session (Run as Eclipse Application...) all works fine.

However, after installing my plugin I am not able to use it. If I use ss in the OSGI console I get following status for my plugin:

1102    STARTING    org.treez.core_1.0.0.201712191435

and if I manually try to start it I get

osgi> start 1102
gogo: BundleException: Error loading bundle activator.

I tried to start a remote debug session, as suggested here: Debugging Eclipse plug-ins

I set a break point in the constructor of my Activator but that break point is never reached.

=> How can I get additional information about why the loading of the bundle activator fails? Is there some log file? Can I somewhere set a logging level to TRACE?

I assume that the issue might be that a resource can be found while debugging the Eclipse Application but not when using the bundled jar. More info, e.g. the name of the resource that could not be found, would be very helpful.

Related questions:

• Debugging Eclipse plug-ins

• CQ5 OSGi bundle does not start:- Activator cannot be found

Answer 1

When plugins fail to start there is normally a message in the .log file in the workspace .metadata directory.

On Linux, Unix and macOS this file and directory are hidden so you may need to do something special to see them.