TDMS Reserve File Size Function Returns Error -68002 on Windows Vista and Windows 7

Updated Dec 5, 2018

Reported In



Operating System

  • Windows

Issue Details

I am using the TDMS Reserve File Size function on Windows Vista or Windows 7 with User Account Control (UAC) on. I am receiving error -68002: "LabVIEW: Failed to reserve file size". 


To use the TDMS Reserve File Size function, you must have administrator privileges of your computer. If the operating system of the computer uses User Account Control, you must also complete the following steps to configure the User Account Control settings:
  1. Open the Windows Control Panel.
  2. Click System and Security in the Category view.
  3. Click Change User Account Control settings in the Action Center section.
  4. In the User Account Control Settings dialog box that appears, move the security slider down to Never notify.
    Caution: Changing the security settings might bring your computer to potential security risks. Click the Tell me more about User Account Control settings link in this dialog box to understand the potential security risks of each setting.
  5. Restart your computer.

Additional Information

The TDMS Reserve File Size function calls the Windows function SetFileValidData, which requires running with administrator privileges to function asynchronously. If SetFileValidData is not called, several problems can arise and asynchronous I/O can appear as synchronous I/O


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