This error occurs when AutoCAD cannot find the acadapp.arx file due to a corrupt Windows registry or portion of the hard disk where this file
resides. The acadapp.arx file contains a variety of functions required by AutoCAD, as well as ObjectARX and ADS applications.
To troubleshoot the cause of this error message:
From the Tools menu, choose Options.
In the Options dialog box, select the Open and Save tab. Make sure that Object Detect and Command Invoke is elected from the Demand Load ARX Apps
drop-down menu.
Check that the support paths in the Options dialog box contain the folder where acadapp.arx is located Copy the acadapp.arx file from the AutoCAD Installation CD to the hard drive to overwrite the existing acadapp.arx file.
Check for another acadapp.arx file on the hard drive by using the Find Files or Folders tool in Windows Explorer. If another acadapp.arx file is found,
make sure that AutoCAD cannot find this file in its search path.
If the error recurs, it is possible that a corrupt registry key in the Windows registry is the cause. If this is the case, you need to uninstall and reinstall AutoCAD.
Before you uninstall AutoCAD, save any menu files, AutoLISP® files, and any other customized files to a temporary directory. Before you reinstall
AutoCAD, reboot the computer and completely remove any directories that remain after uninstalling AutoCAD.
Important: When you reinstall AutoCAD, make sure you reinstall the application to a new directory. If a corrupt registry is the cause of the
error, then installing AutoCAD into a new directory will resolve the problem.