GUI Crashes when editing configuration with 20 or more users

[Bruce]

If your Filezilla server has more than 20 FTP users, the configuration cannot be edited, as this will cause the GUI to crash. To reproduce this, set up a FileZilla Server with at least 20 FTP users in the users.xml file.

In the FileZilla Server GUI, navigate to 'Server -> Configuration.' This action will result in the error message'FileZilla Server Administration Client has stopped working,' causing the GUI to crash.

The event logs record the error below;

Faulting application name: filezilla-server-gui.exe, version: 1.10.2.0, time stamp: 0x67f79269
Faulting module name: filezilla-server-gui.exe, version: 1.10.2.0, time stamp: 0x67f79269
Exception code: 0xc0000005
Fault offset: 0x0000000000027888
Faulting process id: 0x25c8
Faulting application start time: 0x01dbaad15c980f6a
Faulting application path: C:\Program Files\FileZilla Server\filezilla-server-gui.exe
Faulting module path: C:\Program Files\FileZilla Server\filezilla-server-gui.exe
Report Id: 62290dda-3b7e-4ef4-8acb-5bcbbc547faa
Faulting package full name:
Faulting package-relative application ID:

[Bruce]

Screenshot of error

[Tim Kosse]

Cannot reproduce. Could you please attach a dump from the crash? You can find the dumps in the %LOCALAPPDATA%\CrashDumps\ directory.

[Bruce]

Dump of crash

[Bruce]

I've attached the dumb file.

I've successfully replicated this issue on two servers. By editing the users.xml file and reducing the number of users until the file size was below 15 KB, the error was resolved.

I confirmed that the problem wasn't caused by corrupted XML and spent a few hours testing various combinations of users. Additionally, I discovered that commenting out users to leave just 10 still results in a crash. This leads me to believe the issue may be associated with the size of the users.xml file rather than simply the number of users.

Hope this helps.

[Tim Kosse]

I am unable to reproduce this issue even with a users.xml over a megabyte in size. Besides, the XML file itself isn't even sent to the admin UI, but pre-processed data in an internal representation.

Are you able to share a users.xml with dummy data that results in a crash for you?

[Tim Kosse]

I've also prepared an unoptimized, unstripped debug build, you can find it here: https://filezilla-project.org/nightlies_server/2025-04-11/win64-server/FileZilla_Server_1.10.2_win64-setup.exe

Please try this one and once it crashes, again attach the resulting dump.

[Bruce]

I can't reproduce the error with dummy data, but I can provide a users.xml file that does cause the crash that has the passwords removed, but as it contains usernames do you have an email address I can send it to you privately?

[Tim Kosse]

Yes, you can send it to tim.kosse@…

[Bruce]

unstripped debug build dump

[Bruce]

I have attached the unstripped debug build dump.

[Tim Kosse]

We found the issue, expect a new version in a couple of hours.

Until then, avoid usernames starting with a number digit or any other character that sorts less than the less sign.

[Bruce]

Brilliant! Thank you for identifying the cause of the issue and for the upcoming fix.

[Tim Kosse]

1.10.3 has been released.

[Bruce]

I can confirm that the issue has been resolved in version 1.10.3.

Thank you, Tim. I wasn't expecting such a quick fix, so I really appreciate it.