Apple Photos curation and face-detection stuck forever since macOS Big Sur. How to fix?

Apple Photos is stuck forever in face recognition and photo curation.

How can I get it working again?

I) Photo Library Charateristics

I mentioned that I had one main system photo library (being mostly local only, iCloud only for few shared albums) and a private library. And described there characteristics in great detail, to find possible causes. Did all not matter!

II) Main fix strategies found online 2020-2021:

As links here, in detail as individual answers below:

  1. ✅ Fully enable SIP and uninstall unsigned 3rd party Kernel extension(s)
  • Working solution eventually! 🙂
  1. Give it some time
  2. Repair the library
  3. Find corrupted or unsupported files and remove them
  4. Deactivate login items, do some cleanup in cache folders, etc
  5. iCloud on/off/re-syncing based approaches

Give it some time.

  • Let it run overnight with energy saving off.
  • Give it (= the background process photoanalysisd) more time (days, weeks).
  • Variations: Photos.app running, in background, or off at all.

❌ Worked never or only once. Never permanently.

Technically it can be observed that photoanalysisd can run with or without Photos.app running. But some noticed it is important that Photos.app is running but in background and the system needs to be overall idle for a certain time, before photoanalysisd kicking in.

Those who continue suffering observe that photoanalysisd runs periodically, but always only shortly w/o accumulating much CPU time and Apple Photos showing no progress at all. Suspicion is that photoanalysisd chokes on some bad input. But due to lack of a log file or calling it manually with verbose output we can only speculate.