System.UnauthorizedAccessException: Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 80070005 Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)).



1.  Run: mmc comexp.msc /32
2.  Drill down to "DCOM Config"
3.  Locate "Microsoft Excel Application"
4.  Right click and select properties
5.  On the security tab select "customize" under "launch and activation permissions", “Access Permissions” and “Configuration Permissions”
6.  Add IIS_IUSRS and NETWORK SERVICE users
7.  Assign all permissions to the users

如果按照上述步骤配置之后，问题依然存在，则需要确认安装的Access Database Engine是32位还是64位的，程序也需要编译成为对应位的程序。