Error 0x801F001A

Value: -2145452006 | 0x801F001A | 2149515290

What does it mean ?

ERROR_FLT_VOLUME_ALREADY_MOUNTED  
The specified volume is already mounted.
Value: 26 | 0x001A | 0b0000000000011010

Where does it come from ?

FACILITY_USERMODE_FILTER_MANAGER  
User Mode Filter Manager
Value: 31 | 0x01F | 0b00011111

Other Errors for FACILITY_USERMODE_FILTER_MANAGER