Hello, I just spent like 5 minutes trying to figure this out and figured this might be a common question, so just posting the answer here for posterity. If PieFed hasn’t seen the community before you can add it by navigating to Topics -> All Communities -> Add Remote Community.
It seems like unseen communities don’t automatically get added when you try to migrate your user JSON, so be careful to add any remote communities that are missing.
Yeah my import also took a few minutes and then errored out, but it did end up making some progress on my subscribed communities. I tried it a couple more times and then ended up adding the last few subscribed communities over. I don’t know if retrying it was making incremental progress or whether it was hitting the same error every time. It looks like my blocked communities didn’t come over at all though.
Edit: On closer inspection almost all of my blocked communities don’t even exist on Piefed.ca yet, so that’s an interesting wrinkle. I guess I’ll have to wait until they pop up again before blocking them? I don’t feel right telling Piefed.ca to start tracking those communities just so I can block them, lol.
I got mine to import. I’m not averse to a bit of NSWF content, so have Lemmy set to show NSFW, but most of it did not appeal to me so I just blocked the communities as they came up in my feed. I had 567 blocked communities! Once I edited the JSON to remove those and the import worked.