How to save files using Microsoft.Win32.SaveFileDialog with filenames longer than MAX_PATH?

Question

I am trying to save a file:

Microsoft.Win32.SaveFileDialog dlg = new Microsoft.Win32.SaveFileDialog
        {
            FileName = "verylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexampleverylongexample.foo",
            DefaultExt = ".foo",
            Filter = "Foo Bar|*.foo"
        };

Upon pressing Save in the dialog, I receive this:

The filename, directory name, or volume label syntax is incorrect.

even though I have this in my app.manifest:

<application xmlns="urn:schemas-microsoft-com:asm.v3">
  <windowsSettings xmlns:ws2="https://schemas.microsoft.com/SMI/2016/WindowsSettings">
      <ws2:longPathAware>
          true
      </ws2:longPathAware>
</windowsSettings>

as mentioned here: https://learn.microsoft.com/en-us/windows/desktop/FileIO/naming-a-file#maximum-path-length-limitation

Did you try the registry hack from that reference (just for completeness)? — Paul Sanders, Mar 05 '19 at 17:37
I can reproduce this issue using WIN32 API CreateFile2 on 1809 Windows 10 desktop and I'll report this issue via feedback hub. — Rita Han, Mar 06 '19 at 08:41
Feedback hub issue: https://aka.ms/AA4g4r4 You can check and vote up it. — Rita Han, Mar 07 '19 at 02:05

score -1 · Answer 1 · answered Mar 04 '19 at 16:06

So yes, what guys mentioned in the comments means that your Windows doesn't support it.

Starting in Windows 10, version 1607, MAX_PATH limitations have been removed from common Win32 file and directory functions.

Now, to make it cross-Windows, you'd have to create custom file dialog, operating through paths using \\?\Drive:\ style.

How to save files using Microsoft.Win32.SaveFileDialog with filenames longer than MAX_PATH?

1 Answers1