After buying a new harddrive, disabling bitlocker on the old one, moving the data to the new one and booting the system I wanted to re-enable Bitlocker. But all I got after running
manage-bde -on c: -rp
ERROR: An error occurred (code 0x80070002):
The system cannot find the file specified.
NOTE: If the -on switch has failed to add key protectors or start encryption,
you may need to call “manage-bde -off” before attempting -on again.
This error can happen if the file C:\Windows\System32\Recovery\ReAgent.xml is corrupt or cannot be read in any way.
When I tried to open it with a text editor I got the same error. Renaming (deleting) the file solves the problem. The file will be recreated on the next restart or when enabling bitlocker.