mobile

I'm currently trying to update my phone from CM11 to CM12 using TWRP. In TWRP, I factory reset my phone, then flashed the latest CM12 nightly build. However, when I try to flash gapps, TWRP says that it fails. If I try to run my phone normally, I get errors saying that Google Play Services has stopped, Setup Wizard has stopped, etc. I have no idea where I'm going wrong, how can I fix this?