Why WhatsApp spontaneously starts a backup in the middle of the day?

I finally think I found out.
It is connected to date/time as aBochur suggested, but it's not that I changed the date/time of my phone or moved between time zones.

My findings

I have LG G5 and it has a removable battery.

Whenever I takeout the battery and replace it with the second one, when the phone comes up it has an old date/time - can be hours or days before (not sure what's the rule here, maybe previous shutdown?). This, from some, reason triggers a backup on WhatsApp.

Times after startup:

• After 2.5m the phone reception is back and fixes the date/time.


• After 5m WhatsApp creates a local backup.


• Sometimes, not figured out when yet, it also triggers the cloud backup. If it will - it will happen (~around) 30m after the local backup.
  
  
  
  
  • I think it has to do with the time passed from the last cloud backup, but wasn't able to test it deeply yet.
  
  

So, the conclusion is there's nothing to do with it, this is how WhatsApp works and it's backup get triggered after it recognizes a date/time change.

This is the notification that sometimes WhatsApp shows, there's not a full correlation between this notification appearance and the backup trigger.

• 
  

  Your phone date is inaccurate! Adjust your clock and try again.

  
  

  
  
  

  



• Note: I haven't tried anything, this message just appears on those occasions.

The answer will be updated if I'll be able to collect more information about this.