Okay, just for the sake of completeness:
You can capture the log by connecting your phone via USB (using WiFi probably won’t work as the connection gets lost in the reboot),
going to the settings and enabling the encryption.
The phone doesn’t completely reboot - the only part that is being restarted is the user interface. Your USB connection and both adb processes (the one on your phone and the one on your PC) will stay alive.
The first time, I tried to enable the encryption, I got the same error that someone posted here in this thread.
After resizing, everything went well for me.