I can't set the screen lock to "None" or "Swipe" after updating to Android 5.x, 6.0 or 7.x

After updating your Xperia™ device to Android™ 5.0/5.1 (Lollipop), Android 6.0 (Marshmallow) or Android 7.0 (Nougat), you may experience problems setting the screen lock to None or Swipe. This only happens if you set a pattern or a password lock before you update.

To fix this issue, you need to clear the credential storage.

To clear the credential storage

1. From your Home screen, tap the Application screen icon.
2. Find and tap Settings > Lock screen & security or Security > Clear credentials.