File.Exists returns false, even when the file is present in the folder

Question

bool a = File.Exists(archiveDetail["downloadPath"]);

The a is always set to false, even when the file specified is present in the location, when I debug and copy the file path and paste it in the explorer the file is present and its opening, but this methods returns false. Also the length file path is 309 characters, is that the cause of this?

Should the length of the file path be less than 260 characters? Also I have changed the app.confing to consider the files with long paths :

<runtime>
    <AppContextSwitchOverrides value="Switch.System.IO.UseLegacyPathHandling=false;Switch.System.IO.BlockLongPaths=false" />
</runtime>

Why is File.Exists() returning false?

Tried to handle the file paths with more than 260 characters. P.S - the length of the name of file is 134 characters.

I also have tried this [link] Still not working though.

This is the path generated when debugged, when I paste this in explorer the file opens :

C:\Users\a.bhis\Documents\GitHub\Solutio-2000\Solutio\Solutio\Content\SDKs\web\Z10_\Solutions_ZC_265\Zrbeqtqdqkuqenle\SolutionExploer\ABC Privateino\Bhar\CasisInfo\ddtp___p123palsis01.extern_botgurndne_comfi_handbuerer_silly_zzp-e.nsf_5_ZZ73860ZZEZZZ8CZ6701244Z4646_$file_Lassiv+BN2+11-1999.pdf

Answer 1

I've tried and tested this, and it works for accessing files that has long sub-directory structure thus exceeding the path length limit in windows.

For File.Exist() method, you can use this alternative method:

  if (!CheckPath(archiveDetail["downloadPath"]))
     {
      throw new Exception("The export file does not exist!");
    }

 public bool CheckPath(string path)
        {
            if (path.Length >= MAX_PATH)
            {
                return checkFile_LongPath(path);
            }
            else if (!File.Exists(path))
            {
                return false;
            }
            return false;
        }

private bool checkFile_LongPath(string path)
        {
            string[] subpaths = path.Split('\\');
            StringBuilder sbNewPath = new StringBuilder(subpaths[0]);
            // Build longest subpath that is less than MAX_PATH characters
            for (int i = 1; i < subpaths.Length; i++)
            {
                if (sbNewPath.Length + subpaths[i].Length >= MAX_PATH)
                {
                    subpaths = subpaths.Skip(i).ToArray();
                    break;
                }
                sbNewPath.Append("\\" + subpaths[i]);
            }
            DirectoryInfo dir = new DirectoryInfo(sbNewPath.ToString());
            bool foundMatch = dir.Exists;
            if (foundMatch)
            {
                // Make sure that all of the subdirectories in our path exist.
                // Skip the last entry in subpaths, since it is our filename.
                // If we try to specify the path in dir.GetDirectories(), 
                // We get a max path length error.
                int i = 0;
                while (i < subpaths.Length - 1 && foundMatch)
                {
                    foundMatch = false;
                    foreach (DirectoryInfo subDir in dir.GetDirectories())
                    {
                        if (subDir.Name == subpaths[i])
                        {
                            // Move on to the next subDirectory
                            dir = subDir;
                            foundMatch = true;
                            break;
                        }
                    }
                    i++;
                }
                if (foundMatch)
                {
                    foundMatch = false;
                    // Now that we've gone through all of the subpaths, see if our file exists.
                    // Once again, If we try to specify the path in dir.GetFiles(), 
                    // we get a max path length error.
                    foreach (FileInfo fi in dir.GetFiles())
                    {
                        if (fi.Name == subpaths[subpaths.Length - 1])
                        {
                            foundMatch = true;
                            break;
                        }
                    }
                }
            }
            // If we didn't find a match, write to the console.
            if (!foundMatch)
            {
                return false;
            }
            return foundMatch;
        }

This is as per the reference LongFileIssue

The issue of reading the file can be resolved by using the alternative class file LongPath as mentioned in this blog

While using the FileStream however you have to specify the file name, since the LongPath's FileStream name will not be as required.