Press Windows Key + R , type regedit , and press to open the Registry Editor.

Right-click any .dwg file on your computer and select .

Here is a structured guide to resolving this issue, ordered from simplest to most advanced. Immediate Solutions 1. Repair AutoCAD Installation: Go to Windows Control Panel > Programs and Features

Navigate to the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Autodesk\AutoCAD\R24.0\ACAD-4101 (Note: The exact number after R24.0 depends on your regional version). Look for the string value on the right panel.

The error may also be accompanied by a secondary fatal error message referencing an "unhandled illegal access read exception," which typically points to the underlying DLL loading failure.

The error in AutoCAD 2021 is a critical launch failure caused by corrupted user profiles, broken file path associations, or missing Microsoft Visual C++ redistributable packages . This error breaks the application’s initial startup sequence by misplacing or failing to read the primary localized support library. Left ignored, clicking out of this prompt often leads to a secondary "FATAL ERROR: Unhandled Access Violation" crash.

Choose first. If the error persists after a restart, try the Reinstall option. 2. Check for Permission Issues