Error 0x800007DC

Value: -2147481636 | 0x800007DC | 2147485660

What does it mean ?

PDH_CANNOT_SET_DEFAULT_REALTIME_DATASOURCE  
Cannot change set default real-time data source. There are real-time query sessions collecting counter data.
Value: 2012 | 0x07DC | 0b0000011111011100

Where does it come from ?

FACILITY_NULL  
The default facility code
Value: 0 | 0x000 | 0b00000000

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Other Errors for FACILITY_NULL