Data Dictionary Error Detected When Running NI MAX

Updated Jan 11, 2019

Reported In


  • Measurement and Automation Explorer (MAX)

Operating System

  • Windows

Issue Details

  • I get the following "Data Dictionary Error Detected" message when I start Measurement & Automation Explorer (MAX) or when I try to view my devices and software.
  • I'm getting a NI-MAX error having to do with "Data Dictionary" and "Scheme" 
  • I updated to a newer version of National Instruments software and now when I try to expand the devices tree in MAX I get an error saying: Error code MAX SCHEMA 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

How can I resolve this error?


This error message indicates that the 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 MAX database. However, if you are still seeing the error, please complete the following steps to revert to an uncorrupted backup:
  2. Log in as an Administrator or as another user with Administrator privileges and run the MAX Database Corruption Removal Tool. This tool aims to automate the process of removing database corruption for a quicker solution.
  3. Navigate to Start»Run and enter services.msc, right-click on NI Configuration Manager, and select Stop.
    1. If using a real-time operating system, boot into safe mode.
  4. Navigate to the MAX Data folder and delete all config*.* files in the folder.
    1. If using Windows XP, the Data folder located at: C:\Documents and Settings\All Users\Application Data\National Instruments\MAX\Data\.
    2. If using Windows Vista or later, the Data folder is located at: C:\ProgramData\National Instruments\MAX\Data\.
    3. If you cannot see the C:\ProgramData folder, make sure to display hidden files and folders.
  5. Navigate to <MAX>\Data Dictionaries\Last\ and delete all files in this folder.
    1. If using a non-Windows platform, also delete mxs.mxr.
  6. Navigate to <MAX>\Data\mxsCheckpoints\ and find the most recent checkpoint to which 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.
  7. Copy <Data>\mxsCheckpoints\<most recent checkpoint date>.cpt\config3.mxs to the Data folder.
  8. Copy all of the DLL files in <MAX>\Data\mxsCheckpoints\<most recent checkpoint date>.cpt\ to the <MAX>\Data Dictionaries\Last\ folder.
  9. Reboot your machine.

Additional Information

Data dictionary errors can occur after new software from National Instruments is installed on the system. To fix the problem, you need to either install a newer version of the software, or uninstall the current version and install a previous version. For example, if you see the error after installing NI Device Drivers 2007.11, you should either install a newer version (i.e. 2008.03) or uninstall the current version and install a previous version (i.e. 2007.08). You can also use NI Update Service to check for critical updates. To open NI Update Service, go to Start»All Programs»National Instruments»NI Update Service.


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