Error 0x80072179

Value: -2147016327 | 0x80072179 | 2147950969

What does it mean ?

ERROR_DS_NO_BEHAVIOR_VERSION_IN_MIXEDDOMAIN  
The forest functional level cannot be raised to the requested value since one or more domains are still in mixed domain mode. All domains in the forest must be in native mode, for you to raise the forest functional level.
Value: 8569 | 0x2179 | 0b0010000101111001

Where does it come from ?

FACILITY_WIN32  
Provides a way to handle error codes from functions in the Win32 API as an HRESULT. (Error codes in 16 - bit OLE that duplicated Win32 error codes have also been changed to FACILITY_WIN32)
Value: 7 | 0x007 | 0b00000111

Other Errors for FACILITY_WIN32