Data Dictionary Error Detected When Running NI-MAX

Updated Feb 8, 2022

Reported In


  • Measurement and Automation Explorer (MAX)

Operating System

  • Windows

Issue Details

  • I get an error message when I start Measurement & Automation Explorer (NI-MAX) or when I try to select my device in NI-MAX. When this error occurs, NI-MAX freezes and I have to restart the application. The error message that I see each time is listed below. How can I resolve this error?

    Data Dictionary Error Detected:

    An error was detected in a data dictionary on your local system.
    An installed data dictionary is incompatible with a previously installed version.
    This error may have been caused by a recently installed component.

    See the following files for more information:
    C:\ProgramData\National Instruments\MAX\Data Dictionaries\mxsSchemaError.log
    C:\ProgramData\National Instruments\MAX\Data Dictionaries\mssSchema.log

    For more information about this issue, visit and enter the info code MAXSchemaError

    This error is also shown in the following dialog box:

  • I updated to a newer version of NI Software and now when I try to expand the devices tree in NI-MAX I get an error saying: Error code MAX SCHEMA ERROR​



This error message indicates that the NI-MAX configuration data has become corrupted. To resolve this error, follow the steps below to restore the database to the state it was in before any corruption occurred.

  1. First, try resetting the NI-MAX database. However, if you are still seeing the error after resetting the NI-MAX database, please continue to step 2 and complete the steps below to revert to an uncorrupted backup.
  2. Use the NI-MAX Database Corruption Removal Tool if step 1 does not resolve the error. This tool aims to automate the process of removing database corruption for a quicker solution. To use this tool, log in as an Administrator or as another user with Administrator privileges. Note: If you prefer to do this manually, follow steps 3-10 listed below.  
  3. Check for critical updates on any installed NI Software and/or Driver, particularly any recently installed NI Software and/or Driver. You can look for critical updates by opening the NI Update Service. To open NI Update Service, go to Start»All Programs»National Instruments»NI Update Service.
  4. Navigate to Start»Run and enter services.msc, right-click on NI Configuration Manager, and select Stop. This is shown in the image below. Note: If using a Real-Time Operating System, boot into safe mode.
  5. Navigate to the NI-MAX Data folder and delete all config*.* files in the folder. If you cannot see the C:\ProgramData folder, make sure to display hidden files and folders.
    • If using Windows XP, the Data folder is located at: C:\Documents and Settings\All Users\Application Data\National Instruments\MAX\Data\.
    • If using Windows Vista or later, the Data folder is located at: C:\ProgramData\National Instruments\MAX\Data\.
  6. Navigate to <MAX>\Data Dictionaries\Last\ and delete all files in this folder. Note: If using a non-Windows platform, also delete mxs.mxr.
  7. Navigate to <MAX>\Data\mxsCheckpoints\ and find the most recent checkpoint to which NI-MAX can be restored. The checkpoints are backups of the NI Configuration Manager data that allow you to restore the system when a Data Dictionary Error has occurred.
  8. Copy <Data>\mxsCheckpoints\<most recent checkpoint date>.cpt\config3.mxs  of the most recent checkpoint that you located in step 7 to the Data folder.
  9. Copy all of the DLL files in <MAX>\Data\mxsCheckpoints\<most recent checkpoint date>.cpt\ to the <MAX>\Data Dictionaries\Last\ folder.
  10. Reboot your machine.

Additional Information

Data dictionary errors can occur after new software from NI is installed on the system. To fix the problem, you may need to either install a newer version of the software. If a newer version is not available, you may also be able to fix the issue by uninstalling the current version of the software and installing a previous version.

For example, if you see the error after installing NI Device Drivers 2007.11, you can try either installing a newer version (i.e. 2008.03) or try uninstalling the current version and then install a previous version of the software (i.e. 2007.08).