Issue with + and # in filenames when syncing via NC desktop app

📱 Desktop & mobile clients
,
1

We are experiencing sync problems with filenames that contain certain characters. Files with + or # in the name fail to sync when using the Nextcloud Desktop app.

  • Example: test+file.docx or report#1.pdf

  • Files remain unsynced and show errors in the client.

Is this a known limitation or bug in the Desktop app? If so, is there any recommended workaround or planned fix for syncing files containing + or #?

The Basics

  • Nextcloud Server version (e.g., 29.x.x):

    • 31.0.9.1

  • Operating system and version (e.g., Ubuntu 24.04):

    • Ubuntu 22.04.5 LTS

  • Web server and version (e.g, Apache 2.4.25):

    • Apache/2.4.52

  • PHP version (e.g, 8.3):

    • PHP 8.2.27
2

try checking on the devs GitHub

sure, prevent users from naming files with those characters:

  'forbidden_filename_characters' =>
  array (
    0 => '<',
    1 => '>',
    2 => ':',
    3 => '"',
    4 => '|',
    5 => '?',
    6 => '*',
    7 => '\\',
    8 => '/';
    9 => '#';
    10 => '+',
  ),
1 Like
3

So just to confirm:

  • This means there is no way to allow + or # in filenames when syncing via the Desktop app, correct?

We also noticed the same behavior with certain file extensions (like .config, .cs, and bin/ folders) not being synced during a migration. Is there likewise no server-side “allow” option for these cases, and it’s only handled by the client ignore list?

I just want to be sure this is expected behavior and not a bug, so we can set the right expectations for our users.

4 
  'forbidden_filename_extensions' =>
  array (
    0 => ' ',
    1 => '.',
    2 => '.filepart',
    3 => '.config',
    4 => '.cs',
    5 => 'bin',
  ),

honestly, dunno bar having used the DesktopClient… but then you asked for a possible workaround?

reading the docs, this could be what you’re looking for?

settings_general
settings_general798Ă—671 20.7 KB

yip, this is what you’re looking for, global ignore lists:

grafik
grafik557Ă—696 17.2 KB

7

You did not mention your client os and used filesystem.

On serverside you can have filenames incl. emojis in the name.
But client OS are very different.

2 Likes
8

My Ignored file setting:

image
image810Ă—889 16.4 KB

9

Win 10 and 11 and WEBDAV.

10

You don’t write much, so I’m asking again.

Are the files in Nextcloud and you’re having trouble syncing them to the WIN clients?
Or is it the other way around?

Please also read the following:

11

It’s from Windows to Nextcloud.
We’re migrating our data from Windows file servers into Nextcloud.

Besides the + and # issue, we’re also running into sync problems with:

  • very long file names

  • certain file types/extensions: .compiled, .dll, .exe, .config, .htaccess, .ascx, .mdf, .ldf, .resx, .cs, .java, .csproj, .csp

  • folder names like bin and app_data.

12

With the extension, you can search for the code on github, if you click on blame so you can see which commit added this to the code, and the related pull request probably gives a hint.

For the characters, it is often done to be able to sync the files across all platforms and some operating systems/files systems have some restrictions (certain special characters/total path length / ….). If they do not apply for the systems you use, you can adapt these restrictions.

.htaccess in a folder is dangerous in case you use apache as a webserver because you can change the configuration.

app_data is a special folder in Nextcloud, and access to such named folders is probably blocked via webserver configuration. Perhaps it is possible to improve that, so direct access to the folder is still maintained but you still allow such folder names.

Then a few extensions are excluded by the Nextcloud client, but you have already disabled this. I don’t know, I have .dll files synced. In such a case, I’d take a new sync folder, put only the *.dll file, then check the client log, if that is preventing anything, then the server logs.

13

I can’t reproduce this; it works fine for me on both Arch Linux and in a Windows 10 VM. Both are running the latest client version 3.17.2.

grafik
grafik447Ă—129 2.73 KB

Windows had, and in certain constellations still has, a weird character limit for paths/file names. If you have very long paths or files names with more than ~250 characters in total, all kinds of strange side effects would occur. Maybe that has something to do with it?

For the rest of your bullet points, see the post by @tflidd.

14

A few more thoughts/things you can try:

Does Nextcloud also complain about the + and # characters when you upload those files via browser? If so, it’s likely your server configuration that is causing the issue, either the Nextcloud server config, webserver/reverse proxy config, or perhaps the storage where the Nextcloud data directory is located.

In this case we’d need more information about your server configuration to see if we might be able to identify the cause:

  • Web server / reverse proxy configuration
  • OS, database, installation method
  • Nextcloud configuration (the output of occ config:list)
  • Storage configuration
  • Apps you have installed (occ app:list)
  • Any error messages or warnings from the logs (nextcloud.log, and maybe webserver logs)

…which are all things that are asked for in the support template, btw. :wink:

If it works via the browser:

Try to completely uninstall the client on a PC, including deleting the Nextcloud folders under c:\Users\user\AppData\Roaming and c:\Users\user\AppData\local, and then re-install the client and set it up again with the latest version.

If it still doen’t work, maybe also have a look at the client log files under %appdata%\Nextcloud. Additionally you can also create a debug log, which should contain more information: Troubleshooting — Nextcloud latest Administration Manual latest documentation

If that still doesn’t help, you could also try temporarily setting the loglevel on the server to 1 or 0.

15

here is mine:

image
image979Ă—277 69.5 KB
Also tried from the WEB:

image

16

Hi,

Server / Environment details

  • Web server / reverse proxy configuration:
    Apache 2.4.52 on Ubuntu.
    No reverse proxy (Apache serves Nextcloud directly).
    Active vhost: /etc/apache2/sites-enabled/nextcloud-ssl.conf.

  • OS, database, installation method:
    Ubuntu (same host as Apache).
    MariaDB 10.6 with standard Nextcloud DB schema.

  • Nextcloud configuration (occ config:list):
    Main points:
    – check_for_windows_file_names is set to false.
    – filelocking.enabled is false.
    – Data directory: /var/nextcloud_data.

  • Storage configuration:
    Local storage on the same server (no external mounts).

I also tried via the browser and got this result: I can upload other files without any issues via the browser.

image

17

Okay, so we now know that the server returns a 404 error when a file with + or # character is uploaded, so the problem is most likely on the server side.

However, we would still need either a crystal ball or more information from you to help you solve the problem.

This includes logs and full configurations, as I wrote in my previous post, and not just what you think might be important.

Also, is Nextcloud running behind a reverse proxy and/or web application firewall?

Or are there maybe any Files or FilesMatch directives in the web server config with deny or require all denied or similar? What do the webserver logs say (Apache access.log and error.log)?

I mean seriously, come on, what are we supposed to do with that? The content of the file is what would be interesting, you realize that yourself, right? :wink:

18

My thoughts:

Some older Linux OS have difficulties with filenames containing forbidden characters like “+” or “#”, because they in many cases are interpreted as control-characters (artihmetic operator resp comment).

Your Ubuntu is 3 years old and as I see it right, the guys trying to help you use Ubuntu 24 or similar new versions.

I also had issues with OpenSuse 15.1 and older a few years ago, but they mostly were gone with newer versions.

This may be a reason but I am not sure.

Annother reason can be related to the selected System chracter-set.

19

Good news: after adding 'check_for_windows_file_names' => false to config.php, the sync issue with files containing +, #, &, %, and $ has been solved. But there are still sync issues with files such as .exe, .dll, .htaccess, .ascx, .mdf, .ldf, .resx, .csproj, and .csp. and for mac users is the same error for + and # files!It just works for win.

20

Good news: after adding 'check_for_windows_file_names' => false to config.php, the sync issue with files containing +, #, &, %, and $ has been solved. But there are still sync issues with files such as .exe, .dll, .htaccess, .ascx, .mdf, .ldf, .resx, .csproj, and .csp. and for mac users is the same error for + and # files!It just works for win.

21

Hmm, ok, but that feels like kind of an ugly workaround, imho. You probably don’t want to allow characters that actually are forbidden in Windows. What’s strange here is that +, #, &, %, and $ are definitely not forbidden characters in Windows, so they really shouldn’t be blocked even without that parameter.

Yeah, afaik, at least .htaccess may be hardcoded, and if so for good reasons. I’m not sure about all the others, but I tested a few you listed (.exe, .dll, .ascx, .mdf, .csp) by simply renaming a text file, and they all synced fine.

However, I also just noticed that on my instance everything works, and I mean everything, as in literally all characters, even the ones that are actually forbidden in Windows like ? or \. The only exception is .htaccess, which I explicitly have listed in config.php as a forbidden filename. Also, I don’t see the parameter 'check_for_windows_file_names' in my config.sample.php.

So, at this point, I have to admit that I have no idea why our servers behave the way they do. I guess I now need to figure out why my instance doesn’t block anything — not even the characters it actually should — while you need to figure out why yours is blocking too much. :wink:

22

Good to know it’s not a Nextcloud bug – that’s a relief! :blush:
Can you share a bit about your setup? Like what OS you’re on and if you’ve tweaked anything special in Apache, PHP or your config.php (besides the forbidden filename list you mentioned).
Would be nice to compare notes and see what’s different on my side.

Thanks a lot for checking!