Korean characters replaced with underscores in downloaded filenames

[pjb7687]

When downloading files with Korean characters in the filename, the Korean characters are replaced with underscore (_) characters. This issue might also extend to other CJK (Chinese, Japanese) characters as well.

Steps to reproduce:

• Upload a file with Korean characters in the filename (e.g., "한글_파일.txt")
• Attempt to download the file
• Observe that the downloaded filename replaces Korean characters with underscores (e.g., "______.txt")

Expected Behavior:

• The downloaded file should retain its original filename with Korean (and other CJK) characters intact.

I am using Zulip server 9.1 (self-hosted via Docker compose). This happens on the latest Zulip clients across various OS, including Windows, Linux, and Android, so I guess this is a server issue.

Zulip Server and web app version:

• Zulip Cloud (*.zulipchat.com)
• Zulip Server 9.x
• Zulip Server 8.x
• Zulip Server 7.x
• Zulip Server 6.x or older
• Other or not sure

[alya]

Thanks for the report, @pjb7687 ! Reposted in the development community for discussion.

[andersk]

Is this with the desktop/mobile apps, or with the web app in a browser (if so, which browser, browser version, and operating system)?

[timabbott]

Removing the "help wanted" label, since we've not been able to reproduce the issue yet.

[pjb7687]

I have an update.

Today I discovered that this issue only occurs when I upload files via the Android client. I observe the underscores when I download the uploaded file with any client, so firstly I thought this is affected by other clients too, but now I think actually they aren't. Uploads from other clients (web, desktop) are not affected.

[chrisbobbe]

Ah thanks @andersk for transferring this. I'll mark this as a duplicate of #5885 which has our current diagnosis and planned fix.