It is a cabinet file. It is useful for troubleshooting pack because they are self-contained and require no installation. They can be deployed onto Web sites, network shares, or copied on USB keys. It can be executed by WTP. This file is created by Makecab.exe or Cabarc.exe tool. It is located in System32 folder of Windows.
Trouble opening diagcab files on Microsoft Windows?
Advanced File Optimizer
Need help opening a diagcab file? Advanced File Optimizer will do this for you. Opening a diagcab file only takes a few clicks and is very easy, even for novice users.
Compatible with Window XP, Vista, Win7
Need help for .diagcab files call tech experts: (855) 973-2092 (Toll Free, 24*7)