How to Fix Merge Drawings Plugin Loading Issues in AutoCAD

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Here are some common issues you might encounter when merging files between Revit and AutoCAD, along with simple steps to fix them.

Issue 1: The plugin runs normally in Revit, but opens a blank drawing in AutoCAD.

This issue usually happens when the add-in loads incorrectly in AutoCAD. The “Merge Drawings” plugin works seamlessly with both Revit and AutoCAD. When running the plugin in Revit, you should see either a “BUILT-IN” or “STANDARD” status on the interface.

Revit Plugin Status

After you finish running the plugin in Revit, the application will automatically switch to AutoCAD to continue the process. If AutoCAD only opens a blank drawing and does nothing else, it means the plugin failed to load inside AutoCAD.

To troubleshoot this issue, please follow these simple steps:

1. Verify your AutoCAD version: Ensure you are using AutoCAD 2020 or a newer version. Please note that AutoCAD LT is not supported.

2. Check the plugin tab: Look for the custom plugin tab in your AutoCAD ribbon. It should be visible and accessible.

AutoCAD Plugin Tab

If the tab is unavailable, it means the plugin was not loaded into AutoCAD correctly. While this rarely happens, you can easily verify it by attempting a manual load.

3. Test manual loading: Let’s see if the plugin can be loaded manually.

  • In AutoCAD, type the command NETLOAD and press Enter.
  • Navigate to this specific folder path: %AppData%\Autodesk\ApplicationPlugins\BuiltInAcadMergeSheet.Bundle\Contents
  • Open the correct folder based on your current AutoCAD version:
    • For AutoCAD 2020 – 2024: Select the 2024 folder.
    • For AutoCAD 2025 – 2026: Select the 2025 folder.
    • For AutoCAD 2027 and later: Select the 2027 folder.
  • Select the PremiumMergeDwg.dll file and click Open to load it.
Netload DLL selection
  • Type the command INITMLABSPLUGINS and press Enter. You will see the plugin tab appear in the ribbon.
  • Click the Merge Drawings or Layouts to Model command to check if it runs properly.

4. Fix automatic loading issues: If your AutoCAD plugin still isn’t loading automatically at startup, the issue is typically caused by disabled automatic loading, secure mode blocking unsigned code, or missing trusted folder paths.

To fix this quickly, check and update the following system variables in the AutoCAD command line:

  1. Enable APPAUTOLOAD: Type APPAUTOLOAD and press Enter. Ensure the value is set to 1 to allow plug-ins to load automatically.
  2. Adjust SECURELOAD: Type SECURELOAD and press Enter. Set the value to 0 (or 1 provided your plugin folder is in a trusted path).
  3. Set TRUSTEDPATHS: Type TRUSTEDPATHS and press Enter. Ensure the exact folder where your .bundle, .dll, or .lsp file is stored is included in the trusted paths.

5. Reset AutoCAD to defaults: If all the above methods do not work, you can try resetting AutoCAD to its default settings. See: How to reset AutoCAD to defaults.

Issue 2: “FATAL ERROR: ASC initialization failed. Please reinstall the product.” when opening AutoCAD products.

AutoCAD Fatal Error

If you encounter this error message, please try the following solutions:

  • Set the SDI system variable to 0:
    1. Type SDI in the command line and press Enter.
    2. Type 0 (zero) and press Enter.
  • Reset AutoCAD to defaults: See the official guide on How to reset AutoCAD to defaults.
  • Try a different version: Test if the issue persists on a different version of the AutoCAD product.
  • Clean uninstallation: Uninstall the AutoCAD product completely and then reinstall it. A clean uninstallation is highly recommended to resolve deep registry issues.
  • Check for OLE links: If the issue only occurs when opening a specific drawing, check whether it contains any OLE links. Break the links and try opening the drawing again. See: To Break a Link to an OLE Object.