Here is one more issue which was recently killed almost day to find out what was going crazy to let ASP.Net to read excel file using Excel Application.
Tried all different combination to set access for DCOM and other user access settings but none of them worked out. Finally come across solution which worked out in my case was as bellow
For x64 Server : Make sure to create directory
C:\Windows\SysWOW64\config\systemprofile\Desktop ( This was my scenario and we have extended to test it for x86 and it worked in both the cases)
For x86 Server : Make sure to create directory
Thats all you need and you all set to read Excel files from ASP.Net using Microsoft Excel Application
If you come across similar situation and above steps didn’t help you out , please let me know in comment