Jelly bean 4.3: Google account and google contact disappear

[AC Question]

Actually due to some frequent wifi disconnection issue I downgraded from Kitkat to Jelly Bean. The wifi problem is solved. But the new ridiculous problem popped-out. The google account and all the google contacts getting disappear frequently. At this time a warning message will come "Need to set the backup account". I also see a message like "Some program done some illegal activity and it is blocked". When I create the google account again all the contacts appear again. But after few hours (10 or 12 hour) the same problem repeat and google account and all the google contact vanish. The messages "Need to set the backup account" and "Some program done some illegal activity and it is blocked" also come.

Can somebody help?

 

[RumoredNow]

Sounds like Google wants some authentication from you after the downgrade on your device.

Have you tried logging onto that Google account on a computer to see what messages you get there?

Was that phone at one time your go-to # for two step authentication?