Directory.Exists not working for a network path

Question

I have a line of code checking if a directory exists and then getting the list of files in it.

System.IO.Directory.Exists(@"\\Server\Folder\");

I works when I test it (run from visual studio), but when I deploy the web site, it always returns false.

I do the same verification for another folder, on another server (let's say Server2) and it works fine.

I then thought it was an access issue, but the shared folder and network have all access to everyone... Is there another reason why it would not work?

Does the account that IIS runs under have access? – Matthew Apr 17 '12 at 18:24 — Matthew, Apr 17 '12 at 18:24
Is it not able to de-reference `Server`? – David Apr 17 '12 at 18:25 — David, Apr 17 '12 at 18:25

score 32 · Accepted Answer · answered Apr 17 '12 at 18:30

32

When you run the code in Visual Studio it runs under the the rights of your user.

When you run the code in IIS it runs in the identity of the Application Pool which by default is the built in user "Network Service" this is a local user account which does not have access outside the local machine.

The rights on the network share are the first layer, after that the NTFS rights on the directory are checked.

You need to change the identity of the application pool to a domain user with the same rights as your user.

answered Apr 17 '12 at 18:30

Shiraz Bhaiji

64,065
34
143
252

1

It worked on my local IIS for tests too, but the setting were to Application user, so it was taking my local windows user to connect to the network. I set my specific user to the official server's IIS and it worked. Thanks. – Amaranth Apr 17 '12 at 19:36
I don't have a user with rights to all the source and destination directories I need to copy files from and to. Is there any other way to connect to the drives? It also doesn't work with mapped network drives by using the drive letters, so doing a "net use" will also not help I guess. – IngoB Mar 25 '19 at 14:49
Thanks so much. Spent half a day with this headache. – Marius Lukošiūnas Apr 02 '21 at 13:47

score 6 · Answer 2 · answered Mar 30 '16 at 14:32

6

I may be a little late, but i've found that there is a problem on this method of the Directory class. Instead i've used DirectoryInfo with impersonation this way:

new DirectoryInfo(path).Exists

This way you avoid the whole identity change problem, which was denied by our IT area.

I hope this helps somebody!

answered Mar 30 '16 at 14:32

Gonza Oviedo

1,312
15
20

1

This doesn't resolve the issue of impersonation. The main difference is that `Directory` is a static class and `DirectoryInfo` is an instance of a class. – Pat Migliaccio Jun 30 '16 at 16:04
I'll try this. We are getting intermittant failures with a share from a server between the US and Ireland. There is no indication of server trouble. My guess there is a timeout as this server is at times slow to respond. – D. Kermott Aug 25 '21 at 14:42

score 2 · Answer 3 · answered May 02 '16 at 10:30

2

For future references, this also works:

bool result = false;
try
{
    Directory.GetAccessControl(path);
    result = true;
}
catch (UnauthorizedAccessException)
{
    result = true;
}
catch
{
    result = false;
}

answered May 02 '16 at 10:30

Mirko Bellabarba

562
2
13

score 0 · Answer 4 · answered Dec 06 '18 at 01:57

I was was getting this error with code a UNC that looked like this:

@"\Server01\c$\Data\SubFolder"

I made an explicit share and got rid of the c$ and made it look like this:

@"\Server01\TheData\SubFolder"

and it started to work.

I am not 100% sure that is what fixed the permissions problem, but it started to work immediately after making that change.

score 0 · Answer 5 · answered Mar 09 '22 at 23:41

It turned out for me all I had to do when I was adding the network drive was to run the net use ... command from an elevated command prompt. My application runs as administrator so I'm guessing that's probably why it worked after that.

net use G: \\<NETWORK_DRIVE_NAME>\<FOLDER_NAME> /u:<USER> <PASSWORD> /persistent:yes

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