How to Solve Ac1st16.dll Error

Ac1st16.dll is usually associated with the programme AutoCAD. It is a file that controls the 3D graphical features of the program developed by AutoDesk, Inc. Without it, the software will not run properly or function well.


Important as it is,  this dll file can cause series of errors as shown below:

  • “Cannot find ac1st16.dll.”
  • “A required .dll file – ac1st16.dll was not found.”
  • "Cannot start Autodesk ObjectDBX. A required component is missing: ac1st16."
  • "This application failed to start because ac1st16 was not found."


These errors are usually caused by virus removal tool that cleans the virus but at the same time, removes the infected but important file from the system. To solve the issue, it is necessary to get the dll file back.


The easiest solution is to resintall AutoCAD. But the first thing you must do is to ensure that the folder in which this dll file is located is listed correctly in the PATH statement. This dll file is located in C:\Programs Files\Common Files\Autodesk Shared.

Make sure that the PATH statement for this file shows the exact path as listed above. If you need help on how to check the PATH statement, refer to the steps presented below:

  1. Click Start, right-click My Computer, and then click Properties.
  2. Click the Advancedtab.
  3. Click the Environment Variables button in the lower right-hand corner of System Propertiesdialog box.
  4. Check for the path of ac1st16.dll in the Value column.

If the path listed is incorrect, use the Edit button to correct it.

  • Uninstall and Reinstall AutoCAD

Use the built-in Add or Remove Programs utility to uninstall AutoCAD. Next, restart your computer and reinstall the software.

Update AutoCAD with the latest version if the issue persists after reinstallation.


It is recommended that you install a registry cleaner to improve and protect your system. It can detect and clean these dll errors for you. Computer is vulnerable to many virus and malware attacks, and once attacked, numerous errors will come up and