MVC：File.exists返回false

Question

I have a MVC method like this :

public ActionResult DownloadDocument(string filePath){
   //Other stuff
   if (!System.IO.File.Exists(filePath))
   {
       FileLogger.Debug($"DownloadDocument : {filePath} NotFound");
   }
   //Other stuff
}

filePath looks like => \\\\ServerB\\Documents\\General\\Administration\\Doc1.pdf

In local I have a IISExpress (I know that's not great but no choice...) and a data server (Server B). File is on server B. It works really good, I can retrieve my file.

When publishing, I have a IIS on Server A and a the same data Server (Server B). FilePath is still on server B. In this case, I can't retrieve my file because this line returns False :

System.IO.File.Exists(filePath)

Searching a solution, I see ServerMapPath but it's not helping because filePath is on Server B, not Server A.

When I connect myself to the server A, if in the file explorer I put the link \\\\ServerB\\Documents\\General\\Administration\\Doc1.pdf , file is retrieved correctly.

Maybe it's a security problem but don't know where to search...

Thank you for your help

Answer 1

This is most likely an access rights issue. The folder does exist, but .NET can't determine that because the IIS user doesn't have access to the network share.

You can check this by running the IIS application pool as an network user, for example your own account. Don't do this in production scenarios! Create a separate domain account for the IIS user.

Answer 2

Try to create an Application Pool that can access the file from Server B.

Right-Click Application Pool > Advanced Settings

Go to Process Model Section > Identity > Click ApplicationPoolIdentity

From Built-in account. Select > Custom account: > Cick Set >

Set Credentials will popup.

Set your credentials and assign the Application Pool to your application on Server A.

Make sure the User Credential has access to Server B file.

Hope this will help.