100% Data loss when moving between folder

📱 Desktop & mobile clients
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1

Environment

  • Client: Windows 11, Nextcloud Desktop 4.0.5 (Jan 2026)

  • Server: Nextcloud 32.0.5 with two local external storages

    • /SAMBA → mounted on server as /mnt/samba (slow external Samba via fstab)

    • /LOCAL → mounted on server as /mnt/SSD (fast local disk)

  • Desktop client syncs two separate folders: /SAMBA and /LOCAL

Initial state

  • Large dataset fully present locally under /SAMBA (already synced).

  • Goal: move data from /SAMBA to /LOCAL.

Action (on the workstation)

  • In the local Nextcloud folder, user moves data from /SAMBA to /LOCAL.

Expected

  • Safe transfer: data appears on the server under /LOCAL, then the server copy under /SAMBA can be removed without loss.

Actual

  1. Locally, the move is instant (local FS operation).

  2. Client starts upload of the moved data to server’s /LOCAL (slow due to large size).

  3. In parallel, client detects the files no longer exist under /SAMBA and deletes them on the server.

  4. The upload to /LOCAL aborts/fails (timeout/error on slow external storage).

  5. Result: files are deleted on /SAMBA and not fully present on /LOCAL → data loss.

2

Did you try occ files:scan after moving the files?

3

No, because the client has deleted all of the data. Nothing to scan anymore. 100% data loss.

4

What’s with the Trash in web-Interface of your NC-Server?

5

Trash is not installed on the Nextcloud server.

But nothing could be found in Trah because the files had been moved and not deleted.

6

There shall be a Trash by default. See:

Trash
Trash374×717 76.9 KB

here named “Gelöschte Dateien”

Either it’s moved or deleted.

7

This only appears if you haven’t disabled the “Deleted Files” app. But in my case, it is disabled.

8

Okay, so you need to restore the files from backup. If you don’t have a backup, the files are meaningless and their loss is not tragic.

1 Like
9

Of course, it doesn’t matter at all, because you’re just playing around with it. :wink:

But I didn’t expect that you would need a backup just because you want to rename a folder from uppercase to lowercase letters!

10

So a Windows System was involved. But:

Windows treats folder and file names as case-insensitive by default, meaning “FolderA” and “foldera” are considered identical, and you cannot have both in the same location

So what you did must cause Problems.

Addendum:

Renaming Issues: If you try to rename a folder from “data” to “DATA”, Windows might not accept it immediately because it doesn’t see a difference. A common trick is to rename it to something else first (e.g., “data1”) and then rename it to the desired casing (“DATA”).

11

Only within the /SAMBA folder. Here, the folder is deleted instead of renamed.

But it does work within the /LOCAL folder. Here you can rename “TEST” to “Test” on Windows 11.

12

Like always without logs nobody can help

  • collect your client log
  • collect your server log
  • create Github issue describing the problem
  • add you logs there

fortunately desktop client creates very verbose log which is usually useless but in this situation it might help troubleshooting.

13

In Debian 13 with Nextcloud Desktop 3.16.7, you can rename a folder from “TEST” to “Test” in the /SAMBA folder, but an error message appears in the client:

error_renaming_uppercase_to_lowercase
error_renaming_uppercase_to_lowercase896×265 24.7 KB

And then there are two folders in the client: ‘TEST’ and “Test,” even though only the “Test” folder exists on the server:

error_renaming_uppercase_to_lowercase1
error_renaming_uppercase_to_lowercase1495×316 23.9 KB

But at least Linux doesn’t delete the folder, because if you do that with Windows, you’ll need the backup because Windows deletes the folder instead of renaming it.

14

For me its not clear what is the OS of the Host of the /SAMBA folder? Debian 13 with Nextcloud Desktop 3.16.7 seems to be a Client.

I did for Testing reanming on Client Win 11 Prof. a Folder from Podcasts → PodCasts. But unsimilar to you your Test → TEST is a Subfolder of the originally synced folder. LIke Podcasts/Test. So that was different to my Test. In my Test nothing was deleted. Win renamed Podcasts into PodCasts and the Client (Nextcloud-4.0.6-x64.msi) did not even noticed the name change. In the Client PodCasts was still Podcasts.

15

Sorry i forgot to mention that the /SAMBA folder is hosted on a Synology DS220J.

16

I was not familar with Synology DS220J. SO i googled:

The Synology DS220j runs on Synology DiskStation Manager (DSM), a browser-based, Linux-based operating system designed to manage the NAS.

1 Like
17

I suspect both, the Synology DS220J and the NC-Server Hardware are both placed in your local network. So i ask myself why using a SAMBA-share instead of a NFS-Share? Since both systems most likely use a Linux-based operating system, in my opinion NFS is preferable over SAMBA.

1 Like
18

I have now deleted the Samba share and expanded the golden rule:

Don’t mix Samba with Nextcloud!

19

Just wanted to rename a folder from “DATA” to “Data” but the Nextcloud Client has deleted the folder!

100 % data loss (!)

The “DATA” folder is a subfolder of an external Samba share which is mounted via fstab to the filesystem of the Nextcloud server.

Setup see: 100% Data loss when moving between folder

20

You renamed it on the server or client-side?

And is it just the client that deleted the folder on the client, or as well on the server (and SMB)?