Hey there, the logs should give you some additional info (/var/log/graylog/server/server.log). Or if you look at your browser’s developer console, you should get some additional info. FWIW I’m on 4.1.3 and able to import the extractors without issue:
I agree that it’s definitely not intuitive and that’s not an ideal first experience we like folks to have. I think part of the problem may arise from the fact that the repo that houses those extractors is quite old (circa 2.2/4 years ago) and a lot has changed in Graylog in 4 years. So those extractors haven’t been converted to a content pack, they’re just the raw JSON. Ideally, they’d be content packs and you could just import them without having to to worry about the raw JSON.