What is a pin to log into Android?

[Nancy Layton-Cook]

My new (June 2017) Xperia Compact mobile has been switched off for a month because I am abroad. On restarting it, I was not taken to the normal log in screen but a black and grey screen that said "to start Android enter your PIN". I have tried the normal phone security pin, the PUK, 0000, 1234 (and have rung also Vodafone who could not help) and nothing has worked. I have now tried 21 times and am now down to 9 attempts before the mobile automatically goes into a full factory default reset, can anyone help? What code is the phone looking for??

 

[B. Diddy]

Welcome to Android Central! It's your backup PIN. Do you use the fingerprint sensor? If so, the phone will ask for your backup PIN on occasion (like when you do a cold start) for extra security. Hopefully you remember your backup PIN -- it's important!