Error 0x8031004E

Value: -2144272306 | 0x8031004E | 2150694990

What does it mean ?

FVE_E_REBOOT_REQUIRED  
You must restart your computer before continuing with BitLocker Drive Encryption.
Value: 78 | 0x004E | 0b0000000001001110

Where does it come from ?

FACILITY_FVE  
Full volume encryption
Value: 49 | 0x031 | 0b00110001

Other Errors for FACILITY_FVE