Some users have successfully fixed the error by replacing the acismobj20.dbx and AcSceneOE.dbx files in their installation folder with the same files taken from a 32-bit installation or a newer version (like 2024/2025). 3. Reset AutoCAD to Default Settings
To resolve the AcISmObj20.dbx fatal error, try the following steps:
: Use the "Reset Settings to Default" tool found in the AutoCAD folder within your Windows Start menu. Autodesk Community, Autodesk Forums, Autodesk Forum 2. Update Graphics and Hardware Settings Update Drivers : Ensure your graphics card drivers are updated to the latest certified version. Disable Hardware Acceleration : If you can open AutoCAD, type GRAPHICSCONFIG in the command line and turn off Hardware Acceleration GPU Preference