The photos app crashes when I enable backup on a specific folder

This often happens when people enable backup on the "Whatsapp" image folder.

Typically it helps to follow the following steps:

1. Delete the App-data of the Google Photos app as explained here: https://support.google.com/photos/answer/6174018?hl=en&ref_topic=6156061

2. Do the same for the Google Play Services, and also uninstall the updates of this app

3. Restart the phone and update the Play Services

4. It should now be possible to add the folder

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