I'm using a sandboxed solution, this is the error I got when I try to make the txt

Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. sharepoint

This is the code I have for creating and writting on the file

string path = @"C:\pruebas\" + txtNombre.Text + ".txt";
        if (!File.Exists(path))
            using (StreamWriter sw = File.CreateText(path))//here happens the error
        using (StreamReader sr = File.OpenText(path))
            string s = "";
            while ((s = sr.ReadLine()) != null)
  • try without the @, which using means a literal string. Try to spit out the path variable to make sure it is valid.
    – Mike
    Feb 19, 2015 at 19:49
  • 1
    You don't have access to file system from Sandboxed Solution. It is blocked, hence sandboxed
    – eirikb
    Feb 19, 2015 at 19:50
  • I made it a farm solution, and works now, but the problem is that the .txt file is created on the server and not on the user pc
    – Uhcnamuf
    Feb 19, 2015 at 19:51

1 Answer 1


If you need full trust operations in sandboxed code, you can create and use sandbox proxies, as described here, here and here.

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