Double-clicking a DWG file starts a new instance of AutoCAD product

Autodesk Support

Sep 23, 2024

Products and versions covered

Issue:

When a DWG file is double-clicked or opened in Windows Explorer or from other third-party file-management systems to be opened in an AutoCAD product, a new instance of the AutoCAD / LT product is launched. This results in multiple sessions of AutoCAD / LT opening simultaneously.

Environment:

  • Windows 10.
  • Windows 11.

Causes:

  • The SDI (Single Document Interface) system variable is set to 1. The value of the SDI variable determines whether multiple drawings can be opened in a single instance of AutoCAD.
  • DWG files are associated with a specific AutoCAD application (for example acad.exe, acadlt.exe), such as AutoCAD, AutoCAD LT, or DWG TrueView.

Solution:

Try the following solutions in order, testing after each to see if the issue has been resolved.

Install the version of DWG TrueView that matches the version of AutoCAD

See: Where to download previous versions of DWG TrueView. 

Check the SDI system variable

  1. Close all instances of all AutoCAD applications.
  2. Restart AutoCAD. Do not open a drawing.
  3. Create a drawing.
  4. On the command line, type SDI and set the value to 0 (zero). 

Drag and drop the drawing into the AutoCAD Drawing Window

  1. Open AutoCAD.
  2. Open File Explorer and navigate to the drawing.
  3. Drag and drop the DWG into the drawing window.  

Associate DWG files with the AutoCAD DWG Launcher

DWG files should be associated with the AutoCAD DWG Launcher program. See: DWG file type associativity in Windows.
Note: 
  1. Right-click a DWG file > Open With menu > choose "Another app.." > search for AcLauncher.exe - usually in: "C:\Program Files\Common Files\Autodesk Shared\AcShellEx\AcLauncher.exe"  
  2. Click "Always". 
  3. Do the same for the .DXF files.

Change permissions of AcLauncher.exe or acad.exe

  • Elevate permissions of AutoCAD and the AutoCAD DWG Launcher:
  1. Locate the following two files:
    C:\Program Files\Autodesk\AutoCAD 20xx\acad.exe (for AutoCAD LT, the executable is "acadlt.exe")
    C:\Program Files\Common Files\Autodesk Shared\AcShellEx\AcLauncher.exe
  2. Right-click each file and choose Properties.
  3. Select the Compatibility tab.
  4. Select "Run this program as an administrator."  

Edit the Windows registry

Try each of these Windows registry edit solutions (see warning about editing the registry at the bottom of the article).

Registry edits solution 1:

  1. Exit AutoCAD.
  2. Press WINDOWS-R on the keyboard to bring up the Run window, enter REGEDIT and click OK.
  3. Delete these Registry keys:
    HKEY_CLASSES_ROOT\.dwg
    HKEY_CURRENT_USER\Software\Classes\.dwg
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.dwg
    HKEY_CURRENT_USER\Software\Microsoft\Windows\Roaming\OpenWith\FileExts\.dwg
  4.  Reboot the computer.
  5. Associate a DWG file with AcLauncher.exe (C:\Program Files\Common Files\Autodesk Shared\AcShellEx\AcLauncher.exe).

Registry edits solution 2:

The following example uses AutoCAD 2020. The value will differ depending on the version of AutoCAD, AutoCAD LT, or DWG TrueView.
  1. Exit AutoCAD.
  2. Press WINDOWS-R on the keyboard to bring up the Run window, enter REGEDIT and click OK.
  3. Navigate to and select:
HKEY_CURRENT_USER\Software\Autodesk\DwgCommon\shellex\apps\{F29F85E0-4FF9-1068-AB91-08002B27B3D9}: AutoCAD
  1. Edit the keys OpenDdeSvc and PrintDdeSvc to both have the value of AutoCAD.r23.DDE, (Items A and B in the below image). Remember, this is for AutoCAD 2020. It is possible that no number is needed (i.e., change it to AutoCAD.DDE). Alternately, it may be necessary to find and implement the appropriate R value for newer versions of the software. (r24 for AutoCAD 2022, for example.)
  2. If necessary, edit the path to the application which is specified for OpenLaunch and PrintLaunch, (Items C and D in the below image) to make sure it goes to the correct acad.exe.
Registry edit to launch specific AutoCAD as a default
 

Warning!
Problems caused by improperly editing the Windows registry could render your computer operating system unusable. Microsoft provides a wealth of critical information that you need to know about the registry in the Microsoft knowledge base. Use the Microsoft Registry Editor only at your own risk and only after backing up the registry as outlined for your operating system in the Microsoft article How to back up and restore the registry in Windows and in the related solution How to back up the system registry. Additional information about the registry is also contained in the Help topics in the Microsoft Registry Editor.
 

Products:

AutoCAD Products; DWG TrueView;

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