Oracle Message ORA-19137 - XQST0079: It is a static error if an extension expression contains neither a pragma that is recognized by the implementation nor an expression enclosed in curly braces

ERRORXQST0079: It is a static error if an extension expression contains neither a pragma that is recognized by the implementation nor an expression enclosed in curly braces
CAUSEAn error occurred during the processing of the XQuery expression.
ACTIONCheck the detailed error message for the possible causes.