: Navigate to the Control Panel (Windows) or Applications (macOS), select Adobe Illustrator CS5.1, and choose "Repair" to restore missing system files.
For Adobe Illustrator CS5.1 on a 64-bit Windows system, you can usually find this file in one of the following directories: 64-bit version Adobe Illustrator Cs5.1 Amtlib.dll
There are several possible causes of the Amtlib.dll error in Adobe Illustrator CS5.1: : Navigate to the Control Panel (Windows) or