Error 1633 LabVIEW Real-Time Process Encountered an Error and Restarted Automatically

Updated Dec 18, 2023

Reported In


  • CompactRIO Chassis
  • PXI Controller


  • LabVIEW Real-Time Module

Issue Details

Every hour and a half of running my Real-Time code I get the following error:

(Hex 0x661) The LabVIEW Real-Time process encountered an error and restarted automatically. 


To resolve this error, try the following troubleshooting steps:
  • There is a known issue (ID 642073) with NI CompactRIO Device Drivers May 2017 and R Series MultifunctionRIO May 2017. Try the workaround for this or update the device driver.
  • Confirm all dependencies are part of the LabVIEW project.
  • Check the NI-RIO Driver and LabVIEW compatibility.
  • Re-format the CompactRIO.
  • The error may be specific to the hardware. Try with a different CompactRIO controller.
  • A memory leak can also lead to this error. If you think this applies to your context, try the following:
    • Ensure you are closing every memory reference. Any misuse of the references could cause a memory leak.
    • Monitor the CPU and Memory Usage on the Real-Time Embedded Target before, during, and after error to narrow down where the error is occurring. You can try to check if there is any memory abnormality, for instance, if the memory increases constantly until it throws the error.
  • Try disabling the embedded UI for your target by selecting the target in NI MAX and ensuring the Embedded UI tickbox is not ticked. For more information on the tickbox, see Enabling the Embedded UI on RT Targets.
If the above steps don't work, please contact NI Support and provide as much context on the issue as you can.