Updating from cm12 nightlies to cm12.1 nightlies worked but there was a problem with Google Play Services.
Flash cm-12.1-20150420-NIGHTLY-mako.zip
and
gapps-5.1-2015-04-19-17-13-22.zip
as recommended here:
After booting some things don’t work, including GMail, throwing errors about Google Play Services.
The following worked:
$ adb root
$ adb shell
root@mako:/ # mount -o remount,rw /system
root@mako:/ # rm /system/priv-app/PrebuiltGmsCore/PrebuiltGmsCore.apk
root@mako:/ # mount -o remount,ro /system
Get new play services apk from:
$ adb install com.google.android.gms-7.3.28_(1863718-446)-7328446-minAPI21.apk
(Note: this doesn’t install a new PrebuiltGmsCore.apk
in the
location above. But now everything works.)