With some hassle I updated the 2016 firmware on my Lenovo P2 to Android 7 (I think my carrier decided that their own app was more important than security updates).
Now that I wanted to put the TWRP recovery onto the phone instead of the stock one, I find out that the phone is encrypted, which it wasn't before. I have not asked for it (it appears Google does this by default now for Android 7) and I have never entered a password explicitly for encryption.
However, TWRP asks for a password for decryption purposes, I believe.
I use fingerprint/PIN as screen lock. This answer and others suggest it should be the PIN, however while that works fine for a normal startup of the phone, that doesn't work in TWRP.
How would I find or set the right password to use (doubting there is a default password!)?