Error 0x8051002A

Value: -2142175190 | 0x8051002A | 2152792106

What does it mean ?

OPC_E_DS_INVALID_SIGNATURE_XML  
The signature markup in a Signature part does not conform to the schema specified in the OPC or XML-Signature Syntax and Processing (http://go.microsoft.com/fwlink/p/?linkid=132847).
Value: 42 | 0x002A | 0b0000000000101010

Where does it come from ?

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

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