Tim Mackey's Weblog

Ran into a permissions problem today using Excel interop code from within ASP.Net, which had worked fine from a windows forms application.
Thanks to 'Frosty' for his post which explains how to enable the appropriate permissions, reproducing it here in case the link ever goes down:

From command prompt / start->run... type dcomcnfg

Select Component Services->Computers->My Compter->DCOM Config

Scroll down and select Microsoft Excel Applicaton

Right click on Microsoft Excel Applicaton and select properties.

Select the Security tab

In Launch Permissions group box click Edit button.

Add the appropriate user for your particular situation. In my case, I
selected MyDomainName\Domain Users.

Make sure that Allow check box is checked for your appropriate user.

Click OK

In Access Permissions group box click Edit button.

Add the appropriate user for your particular situation. In my case, I
selected MyDomainName\Domain Users.

Make sure that Allow check box is checked for your appropriate user.

Click OK

Excel interop will now work via asp.net