Arch Linux

Description:
Unable to send attachments. What this means: after I drag a file into a chat, it says "Unable to load selected attachment." and the GUI representation of the attachment stays there with a loading indicator, as on the given screenshot. (Sometimes it can be canceled by clicking "X" on it, but sometimes the only way to get rid of it is to type some text and send a message.)

This happens when both of the following is true:
1. There are non-Latin characters (e.g. кириллица) anywhere in the path of the file;
2. Signal is NOT started from terminal

I'm using KDE on X11, haven't tested other DEs.

Some time ago I tried reporting it to upstream, but they rejected the report, stating that
> It looks like you are using an unsupported version of Signal. Due to our limitations as a non-profit organization we can only provide support for the version we provide at https://signal.org/download/#. 

Additional info:
* package version(s)
5.63.1-2
Multiple past versions were also affected

* config and/or log files etc.
Did not notice anything relevant in logs

* link to upstream bug report, if any

Steps to reproduce:
1. Launch signal-desktop by an icon on KDE Icons-only Task Manager
2. Select a chat (could be "Note to Self")
3. Select a file in Dolphin that has Cyrillic letters anywhere in its path
4. Drag&drop that file from Dolphin to signal-desktop