Errors Accessing Mail Files on Remote Network Drive

I am trying to backup a remote web server, connected as a Network Drive via SSH. The only files that have issues are email. All of the errors resemble this:

Aug 17, 2023 2:29 PM: Error reported while accessing file: W:\mail.durk@tomoffinland_org\cur\,S=163577,W=167807$cl$2,FSs
{“ClassName”:“System.IO.FileNotFoundException”,“Message”:“Could not find file ‘\\?\W:\mail\.durk@tomoffinland_org\cur\,S=163577,W=167807$cl$2,FSs’.”,“Data”:null,“InnerException”:null,“HelpURL”:null,“StackTraceString”:" at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)\r\n at System.IO.File.GetAttributes(String path)\r\n at Duplicati.Library.Utility.Utility.d__23.MoveNext()“,“RemoteStackTraceString”:null,“RemoteStackIndex”:0,“ExceptionMethod”:“8\nWinIOError\nmscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089\nSystem.IO.__Error\nVoid WinIOError(Int32, System.String)”,“HResult”:-2147024894,“Source”:“mscorlib”,“WatsonBuckets”:null,“FileNotFound_FileName”:”\\?\W:\mail\.durk@tomoffinland_org\cur\,S=163577,W=167807$cl$2,FSs",“FileNotFound_FusionLog”:null}
Visit us onDuplicati forumGithubFacebook

Duplicati’s goal is to backup local drives to the cloud. However, what you want is to backup cloud to the cloud and use emulation softwares to make appear a remote resource as a local drive to serve as a backup source to Duplicati. This is working only in the case where the emulation is perfect or nearly perfect. In practice, this is the case only with remote CIFS (Windows network) resources, on Windows and using Samba on other operating systems. Other cases of emulation are usually not working fully and as such can’t be used.

Sorry, I am backing up the network drive to a LOCAL drive.

There is no problem in backing up to a local drive, the problem is emulated local drives as a source.

This is presumably some sort of Windows add-on that’s not working well enough. What is it?
You can certainly poke at it, e.g. from Command Prompt with noted path to see what it does.
Do that as whatever user Duplicati is running as. You can also test variations, e.g. omit \\?\
DOS device paths like that necessary to avoid some Windows weirdnesses in path handling.