A data processing system includes exception handling circuitry to detect attempted execution of an exception-triggering processing operation which includes transfer of a data value with a given register of a register bank. Upon detection of such an exception-triggering processing operation, syndrome data is stored within a syndrome register characterising the exception-triggering processing operation with that syndrome data including the data value. The value may be stored into the syndrome register upon occurrence of the exception in the case of an aborting write instruction. The data value may be stored into the syndrome register by emulating code triggered by exception in the case of an aborting read instruction.