Question

Needed to write a server text file as the output of a business process initiated by ASP.net app.
The text file writing code is in a library file using standard stream code

All worked OK in IDE.

Publish and it falls over trying to write file. IIS is reluctant to write to the file system.

Much rummaging around and hair pulling finally led to a solution. It is not pretty and only applicable in a situation where you have control over the Webserver.

Answer 1

Just saw your answer.

It doesn’t need to be inside your inetpub or wwwroot directory for that matter, it could be anywhere, as long as security permissions are set correctly for the user under which the application is running as.

But this is actually desired. If not just imagine the consequences of allowing write access anywhere.

Also, there’s no need for the virtual directory. You could create a directory like C:\ProcessOutput, and grant permissions accordingly and it should work just fine.
Another option, would be to have a service account created, and impersonate as that user within your application only for when you need to write that output file.