Ok did u create a backup in Google or anywhere. But thats strange. Normally when there is a software update nothing like this ever been seen. I always create a backup of my phone one does not know the system.
You probably saved your contacts to your phone by default and turned off Samsung Cloud backup, which was a silly thing to do. Always save contacts on Google, or let Samsung Cloud back up your phone at will. Don't be stingy with data. If you haven't done this, just delete your contacts cache and data and sync from backup and Google. To check if your contacts are on Google, log in to Gmail and see contacts. To see if Samsung backs them up, use Smart Switch and Samsung Cloud settings to see the backup status and restore a backup from before the update.
