Error 0x8051003E

Value: -2142175170 | 0x8051003E | 2152792126

What does it mean ?

OPC_E_MC_UNKNOWN_NAMESPACE  
The MustUnderstand attribute of an element contains a namespace that is not recognized.
Value: 62 | 0x003E | 0b0000000000111110

Where does it come from ?

FACILITY_OPC  
Open Connectivity Service (Package Consumption)
Value: 81 | 0x051 | 0b01010001

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