File extension CLS (.CLS) information

Windows cannot open CLS files?

If Windows is unable to open file extension .CLS you may have registry related errors or may not have the appropriate program installed. We strongly recommend that you run a free registry scan.

Appropriate program:

The .CLS file extension identifies a Program Class file which forms a part of a Visual Basic Project. This file may contain object related data for source code authored by this development environment.. Incorrect associations are the cause of many file extension errors. Scan your system to prevent, identify and repair CLS file extension association errors.


  • Performance: To optimize memory and CPU usage for CLS files run a free performance scan.
  • Stability: Fix CLS errors to make your system and applications more stable.
  • Drivers: Scan your PC for the outdated drivers which lead to system errors and slowdowns.

You are currently viewing the detail page for ABF file extension. This page contains a detailed description of the ABF file type, software tools to help resolve file association errors in the Windows registry together with relevant system utility applications and other related information.