Osetup.dll file is a DLL file that is associated with the Microsoft Excel 2010 in your Windows. The file is very much important for the proper running of some applications. When the Osetup.dll file gets corrupt or removed from the computer, you may get Osetup.dll is missing error in Windows. Sometimes due to the occurring of this error issue, you may get problem accessing with a particular application or to access the whole computer. You can say that the error is very much dreadful and annoying for the sake of your computer. But you need not to be worry about the problem. You can fix the Osetup.dll was not found error in your computer with the help of the manual fixing given here in the article or you can also fix the issue automatically after installing Advanced System Repair tool in your Windows.