The supplied option --auth-username is not supported and will be ignored"

Slimat · December 13, 2025, 2:18pm

Hi All

I am new member and have been running Duplicati for a few months in a docker under UnRAID.

However there was a new release a couple of weeks ago, so I updated and now the installed version is 2.2.0.1 - 2.2.0.1_stable_2025-11-09

After the update, I immediately started getting the following error…

LimitedWarnings: [

2025-12-13 01:00:00 +00 - \[Warning-Duplicati.Library.Main.Controller-UnsupportedOption\]: The supplied option --auth-username is not supported and will be ignored,

2025-12-13 01:00:00 +00 - \[Warning-Duplicati.Library.Main.Controller-UnsupportedOption\]: The supplied option --auth-password is not supported and will be ignored \]

However the backups do still seem to be completing.

My setup is that I am backing up to a local USB drive and have set it up using encryption - hence the username/password requirement.

I did remove the

auth-username=

auth-password=

options and tried running again… and unsurprisingly I got the following error…

2025-12-09 01:00:44 +00 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Backup has failed RemoteListVerificationException: Found 68780 files that are missing from the remote storage, please run repair

So, I re-added the auth-username & auth-password and the backup runs again, with warnings.

I created a test file to make sure that the backups are working and recoverable… when the automated backup ran, the file backed up… so I deleted it and tried to restore it and the file was recovered… BUT the recovered file cannot be edited or deleted by my user… it is locked to administrator - so I had to edit, then “save as” - delete the original file (user an admin profile) and then rename the “saved as” file to the original filename.

I have asked for help on the UnRAID support page ([Support] Linuxserver.io - Duplicati), but not had any help solving this yet.

Can anyone advise what is going on? If, as I suspect, the encryption option has been removed from local storage, I would be happy to remove the encryption as the local USB backup media is very unlikely to be stolen… but how do I remove this security and get the backup working properly again, without losing all my previous backup versions?

Or, is there a way to roll back to the previous (unknown) version to regain these features - without losing backup versions.

Many thanks for reading and hopefully someone can offer some help.

Thanks

Slimat · December 14, 2025, 12:15pm

[UPDATE]

OK, have done some more investigating and while I can’t explain it… I will outline in case anyone else has the same issue…

As well as the backup which is showing a warning, I have a number of other backups created identically backing up other users data and they all have the same destination USB drive (each in individual subfolders), using encryption - however theirs all run correctly with no warnings or errors.

So, as I have not been able to get any help, I re-created my backup using a different name (name_2) and set everything identically and am now running it. Prior to running it, I tested the backup destination on the new backup and it passed OK. However if I click Test Destination on the backup which is giving the warning, I get this message;

Error writing file: duplicati-access-privileges-test.tmp, error: Access to the path ‘/duplicati-access-privileges-test.tmp’ is denied.

So, I am hopeful that by re-creating the backup which is giving the error, everything will start again normally. Sadly I have resigned myself to the fact that I will lose all the previous versions - but at least I will have a working backup, for the moment, going forward!

If anyone has any ideas why this has happened to two of my five backups please let me know as I would like to avoid it in the future.

I will remove the schedule on the failing two backups to stop them running any more and then if there is still no help, at a point in the future I will delete the old backups as they total nearly 2Tb, which is a big chunk of my 8Tb USB backup drive!

Thanks

ts678 · December 19, 2025, 3:28pm

Welcome to the forum @Slimat

I got more confused starting there. For Duplicati to do encryption, you set:

1. Basic configuration

The encryption setup allows you to choose an encryption method and a passphrase.

  --passphrase (Password): Passphrase used to encrypt backups
    Supply a passphrase that Duplicati will use to encrypt the backup
    volumes, making them unreadable without the passphrase. This variable
    can also be supplied through the environment variable PASSPHRASE.

The files resulting from Duplicati AES encryption end with a .aes suffix.
They can be written to normal local USB drive without login, yet you add:

Authentication (Windows Only)

To use authentication, provide the --auth-username and --auth-passwordarguments to the query

and though I use neither Unraid nor Docker, neither are Windows SMB.

Could you clarify what encryption you’re using and why you need login?

You seem to be manually editing options. Are you using CLI somehow?

Slimat · December 19, 2025, 4:31pm

Hi @ts678

The docker installation sits on a Linux based NAS system called UnRAID.

Once installed some parameters are configured in the docker setup… e.g. /source in the docker is typically mapped to /mnt/user/ in the UnRAID NAS, so that in the docker you can use /source/folder as the location of the files you want to back up… all the Duplicati configuration is done via a web based GUI;

Within this configuration is a setting to encrypt your backups… so if you are doing a backup to a cloud solution (Google Drive, etc), you can be assured that nobody else can intercept the upload, or hack the host and get your data.

In the GUI the AES encryption password is set in the General / General Backup Settings section;

The username / password is set in Destination / Backup Destination settings;

I have several backups which run on different days and different frequenciues, they back up to an 8Tb local USB drive and are also encrypted. However after running the update which I mentioned, my main backup and one other both produce this warning. But, the other 4 which use the same encryption work fine… so it seems only 2 have developed this fault.

I have deleted my main 2Tb backup and recreated using identical settings and it is now working fine again. The downside is that I have lost all my previous versions… which as it is personal data and not business information it isnt too important.

Hopefully this answers some of your questions.

Thanks

Slimat · December 19, 2025, 4:32pm

If you wanted to see the setup procedure I am using there is a very good tutorial by SpaceInvaderOne which can be seen here…

I have linked directly to the USB backup details.

ts678 · December 19, 2025, 5:21pm

It clarifies slightly, but why are you trying to use a Windows SMB client login username and password with a local USB drive on a non-Windows system?

I don’t know if option validation changed, but that’s not going to do the login, however I don’t see any need to do a login. This login is only for SMB client.

How are you editing or even seeing the options you speak of using the GUI? Destination screen three-dot menu?

Although I’d have thought those two options would not be relevant, the test says otherwise. Where are you editing? On the URL (begins with file://), or later?

There have been some changes in the new UI (which you aren’t in) on preferred location. It prefers attached-URL instead of a standalone with the double dashes.

There is also a new Duplicati SMB client. Previously it used the one OS provided, which shouldn’t matter on local USB, but so neither should your login credentials.

So multi-user Linux system. Does that have something to do with the credentials? Primary point of surprise was the idea that it had something to do with encryption.

I watched that chapter and saw the Username and Password fields were blank.

I know it backs up all the permissions, including the user. Did you check box:

Slimat · December 21, 2025, 10:25am

I thought this had something to do with the encryption on the destination media (usb/cloud, etc)… but now you mention this, I seem to recall that because the SMB shares I am backing up on the NAS box are protected with a username/password when I first set this up without putting the SMB username/password in here it didnt have permission to access the SMB share, so couldnt backup.

Now you mentioned the new UI (which I can select by clicking a link in the UI), I looked and these options are not obviously present… but in the old UI they were visible by clicking on the drop down menu from the right of the backup name on the home screen and then clicking on Configuration: Edit and then clicking on the Destination tab…

UnRAID is a NAS solution which also allows Dockers & VMs… so I am not sure this is a multi-user Linux system in the way you think. There are multiple users SMB shares in my UnRAID setup so different family members can store their data… then Duplicati (installed in a Docker in same UnRAID system) has several backup rouines which access the individual users shares and backs them up onto the USB storage media. The two parents SMB shares are protected with username/password to stop any other user accessing our private data.

Yes, from memory I think when I first created a backup it wouldn’t access the password protected shares, so I populated the Username/Password field in Duplicati and it started working. I assumed that in the tutorial I was following that the share/s being backed up were not password protected and hence these were blank (this could be an incorrect assumption on my part)

Yes, I tried with & without this box ticked… however I tried restoring a test file from the new UI today with this option ticked just now and it allowed me to edit & save the file properly… so I am not sure why this wouldn’t work before.

I think I may have not understood correctly what the auth-username and auth-password settings are for, although it was odd that they seemed to allow access to my protected SMB shares… but for the moment it seems that this is working OK, so I will leave well alone until something else goes wrong. Just for knowledge… does anyone know what the auth-username and auth-password settings in the old UI are actually for?

Thanks

ts678 · December 21, 2025, 1:43pm

Exactly your old use, if it was Duplicati getting Windows to authenticate to NAS.

github.com/duplicati/duplicati

Duplicati/Library/Backend/File/FileBackend.cs

ac83beff6


      
          /// Pre-authenticates against the remote share if necessary.

          /// </summary>

          private void PreAuthenticate()

          {

              if (!OperatingSystem.IsWindows())

                  return;

          

              try

              {

                  if (!string.IsNullOrEmpty(m_username) && m_password != null && !m_hasAutenticated)

                  {

                      Win32.PreAuthenticate(m_path, m_username, m_password, m_forceReauth);

                      m_hasAutenticated = true;

                  }

              }

              catch

              { }

          }

The old UI shows fields even if not needed. In the video they were empty.

The general design choice of the new UI is apparently to trim fields down.

The new UI allows them in Advanced options of Destination, available as:

Neither UI immediately labels those as auth-username and auth-password. Seeing the GUI-internal (and CLI) options can be done on the three-dot menu:

The old UI calls the entry fields Username and Password, which equate to URL options auth-username and auth-password. The new UI only shows help text.

This is one of several mysteries mentioned. Please post if you want further help.

Slimat · December 21, 2025, 1:58pm

@ts678 Thanks for all the advice… I will mark this as solved for the moment and hopefully some of the above will be useful if anyone else has similar issues.

Thanks

ts678 · December 21, 2025, 8:39pm

If it was the exact same file, that’s another mystery, however if it was a different file, there’s a slight chance that it was old enough to have come from SMB on Windows which would have Windows metadata which couldn’t be applied in your first restore because Duplicati on Linux wouldn’t know how to apply Windows-format metadata.

The reason I say slight chance is because the pathname format can also interfere, and it’s very difficult but arguably possible to continue a Windows backup on Linux.