ADB backup and restore

I saw an article on Reddit about how ADB backup can be used in migration.  So I thought I checked it out.  The command is
adb backup -f <filename> -full
I ran and kept a copy just for fun.  A few days later, while I was changing Google Play Services, the whole phone locked up.  I could get it to boot and it kept stuck at the OnePlus logo, even after clearing the cache.  Resetted the phone and restore partly from Google Play and Titanium Backup.
Then I remembered my ADB backup and restored that.  The phone came back, with most of the settings.  Some did not.

What was restored

  1. WiFI and bluetooth
  2. Most application settings and data
  3. SMS and Llama
  4. Ringtones selection
  5. Display timeout

 Did not restore

  1. Display font size,
  2. Whatsapp group conversations, some have chunks of missing entries.  I fixed this by restoring from the nightly backups.
  3. The restore also caused Play store to hang, cannot install new applications.  Full reboot to clear.

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