The http header '%1' is reserved and cannot be modified

Error constant SQLE_HTTP_HEADER_ATTRIBUTE_RESERVED_XXX
ODBC 2 State ERROR
ODBC 3 State ERROR
Parameter 1 The header causing the failure.
Severity 16
SQLCODE –1094
SQLSTATE WW070
Sybase error code 13421
Probable cause

The specified http header is reserved and cannot be modified.