Solution to Ac1st16.dll Error

The ac1st16.dll file is recorded to be associated with the AutoCAD program and other programs developed by AutoDesk, Inc. The main function of this dll file is to control various 3D graphical features of the program developed by AutoDesk, Inc.

DLL Issues

You may encounter any of the error messages listed below in relation to this dll file:

  • “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."

You are likely to receive any of the above dll error messages or any other form of dll issue in relation to this file when you install/reinstall some Windows applications, start your computer, or shut down your computer.

Let’s take a look at common causes of ac1st16.dll errors:

  1. The dll file is corrupt – Windows, at times, can save files incorrectly and corrupt them. As a result, programs are unable to access the required file and an error is reported whenever an attempt is made to read the corrupt dll file.
  2. The dll file is outdated – Some older version of software may have overwritten this dll file. As a result, the newer version of the software installed on your computer is unable to access this dll file.
  3. The dll file is not in the right location – When a dll file is moved from its default location, software is unable to read the DLL file even when it is present on the hard disk.


To fix the issue, we recommend you perform the following steps in the sequence they appear in this article.

  • Ensure the PATH statement for this dll file is correct

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 Advanced tab.
  3. Click the Environment Variables button in the lower right-hand corner of System Properties dialog 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.

  • Run a Registry Scan

The Windows registry is a central database that contains reference locations for all dll files present on your hard disk. At times, this list of locations may get corrupt. As a result, Windows is unable to load the dll files it requires and instead returns an error. Use a reliable registry maintenance software and run a thorough registry scan to correct DLL errors occurring due to registry-related issues.