The release of this update via the updated updater app was a mistake! 
The OS was not officially approved by Google yet. That doesn’t mean it’s not safe to update, but if you like to follow rules better wait. I’m sure @Douwe will elaborate soon. PS: Official update won’t come for at least another week!
#Info about the update:
This is a wiki
- 17.04.3 is the long awaited marshmallow update!
- The update shouldn’t erase any data if you come from stock FP OS, but it’s always good to have a recent dic:backup
- Marshmallow comes with a slightly different recovery mode. Check out dic:recoverymode to see how to navigate and use it.
- We haven’t written an Android 6 specific updateguide (yet), but this one is still a good source to check for troubleshooting and general tips.
- Check out marshmallow topics in #fairphone2help to see what issues can arise during the update.
- E.g. bootloops
#Before upgrading
- Perform a dic:backup
- Re-enable the Google App
- Undo all System and Boot modifications
- Load the battery
- Cool down the phone and be prepared to keep it cool even if CPU is at max capacity.
->This will all help you avoid ending up in the above linked bootloop.
#After upgrading:
- Set the Assist app to None if you want to disable the Google App again: Go to Settings / Apps /
/ Default Apps / Assist & voice input / Assist app and set that to None. Even if it already says None, open the menu and explicitly select it! - As for system modifications you’ll need to undo them before any OS update.