C# Can't Access File Because It Is Being Used By Another Process

Question

This is my MVC controller to upload an image. I'm trying to check if the file exists, then deleting the old one and saving the new one if it does. I get the error at System.IO.File.Delete() telling me the file is in use already, but I can't figure out where I left it open and how I might close it.

[HttpPost]   
public ActionResult UploadImage(int? id, HttpPostedFileBase file, EmployeeViewModel employee)
{
    Employee employeeData = db.Employees.Find(id);
    if (file != null && file.ContentLength > 0)
    {
        // Assemble File Path/Extension String
        string[] fileSplit = file.FileName.Split('.');
        string extension = fileSplit[1];
        var fileNameNew = "employeeImage-" + id + "." + extension;
        var path = Path.Combine(Server.MapPath("~/Content/employeeImages/"), fileNameNew);

        var fileExists = System.IO.File.Exists(path);

        if (fileExists)
        {
            System.IO.File.Delete(path);
            file.SaveAs(path);
        }
        else
        {
            file.SaveAs(path);
        }

    }
    return RedirectToAction("Edit", new { id = id });
}

this might sound stupid, but I will ask anyway. where did you choose the source image to upload? I haven't done ASP.NET for a long time, so I don't remember how to do upload like that, but in the past, I always have to write a httphandler to deal with file upload. another quick thought, you don't have to delete the existing file, just save it to a new file, adding a timestamp, so you keep the employee old photos all the time (see if that works) — sowen, Jan 05 '16 at 15:51
I add it via a webpage and a file input element. I'll consider trying to skip deleting and going with a timestamp, I was trying to use a simple naming convention of just 'employeeImage-ID.extension' to make file retrieval easy, but I could add a timestamp and search for the most recent one with the matching ID upon retrieval. — ttante, Jan 05 '16 at 16:00
Is there any web methods or other code that retrieve the image (not the url) that leave it open as a stream? You can also use a command line program named `handle` by `sysinternals` that can show you which process has a file open. You can use this for manual troubleshooting to figure out what has the file open. https://technet.microsoft.com/en-us/sysinternals/handle.aspx — Igor, Jan 05 '16 at 16:30
Yes, I'm seeing this comment just after I realized that my issue had to take place inside of the GET request controller that serves the page to which I was trying to post to since I couldn't find any issue with my POST controller. — ttante, Jan 05 '16 at 18:16

score 1 · Accepted Answer · answered Jan 05 '16 at 20:04

1

There is probably a (web) method (like a GET request) or other code that retrieves the image (not the url) that leaves it open as a stream.

answered Jan 05 '16 at 20:04

Igor

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score 0 · Answer 2 · edited May 23 '17 at 12:15

0

The most likely answers would be that either:

The file is located on a network share and someone else is genuinely using it (is it a virtual directory?).
IIS/ your web server is locking the file (see Does IIS 6/7 lock image files whilst they're being served?
You are uploading the same file as you are writing to (apologies if this sounds patronising but you need to cover all options!)

edited May 23 '17 at 12:15

Community

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answered Jan 05 '16 at 16:19

strickt01

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score 0 · Answer 3 · answered Jan 05 '16 at 18:13

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Since I couldn't find the issue with my POST request, I realized it had to be in the GET request that was taking me to that page. Turns out I was calling Image.FromFile() and not closing it in that GET request.

answered Jan 05 '16 at 18:13

ttante

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C# Can't Access File Because It Is Being Used By Another Process

3 Answers3