Drag-and-drop upload fails to upload multiple files with the same size

[dodaa08]

Description:

When dragging and dropping multiple files with the same file size into a channel, only one file gets uploaded. The deduplication logic uses only file.size as the unique key, causing files with identical sizes to be treated as duplicates and silently ignored.

Steps to reproduce:

1. Create two text files with the same size but different names and content (e.g., echo "Hello World 123" > file1.txt and echo "Different Text!" > file2.txt - both 16 bytes)
2. Open any channel, team, or direct message
3. Drag and drop both files simultaneously into the message input area

Expected behavior:

Both files should be uploaded and appear in the chat.

Actual behavior:

Only one file is uploaded; the second file with the same size is silently ignored.

Screencast.From.2026-01-08.23-01-46.mp4

Server Setup Information:

• Version of Rocket.Chat Server: 8.1.0-develop
• Operating System: Fedora Workstation 41
• Deployment Method: Local development
• NodeJS Version: 22.16.0

Client Setup Information

• Desktop App or Browser Version: Chrome
• Operating System: Fedora Workstation 41

Additional context

The deduplication logic in useFileUploadDropTarget.ts uses file.size as the unique key, which causes different files with the same size to be incorrectly filtered out as duplicates.

[shouryapratap132006]

Hi,

Thanks for reporting this issue , I was able to reproduce the behaviour and confirm the root cause.

The current drag-and-drop deduplication logic uses file.size as the unique key, which causes different files with identical sizes to be treated as duplicates and ignored. This explains why only one file gets uploaded when multiple files of the same size are dropped together.

I’d like to work on fixing this by updating the deduplication strategy to use a safer composite identifier ( eg. file name + size + lastModified), which will correctly distinguish files without adding unnecessary complexity or performance overhead.

If no one is currently working on this, I’d be happy to take it up and submit a PR.
Please let me know if this approach sounds good or if you’d prefer a different strategy.

Thanks!

[dodaa08]

@shouryapratap132006 isn't there a PR already to it ?

[shouryapratap132006]

Thanks for the quick fix and PR link!

I’ll review PR #38109 to understand the approach used and learn from it.

Happy to help with testing or follow-up improvements if needed.

[casalsgh]

Thinking out loud: Does it work if you drop multiple different files today?
Haven't tested it yet, just wondering.

[dodaa08]

Let me check @casalsgh

[dodaa08]

Thinking out loud: Does it work if you drop multiple different files today? Haven't tested it yet, just wondering.

Yeah it's working fine now
on 8.1.0-develop

[casalsgh]

FYI - shared the bug reported with internal engineering team.

[dodaa08]

FYI - shared the bug reported with internal engineering team.

Alright, thanks!

[KevLehman]

Can u check if this is fixed after #32703?

[dodaa08]

Can u check if this is fixed after #32703?

Sure, let me see

[dodaa08]

Can u check if this is fixed after #32703?

@KevLehman Yes, both drag and drop and selecting multiple files at the same time seems fine, I on 8.2.0-develop rn

Screencast.From.2026-02-19.00-52-17.mp4

[dodaa08]

Can u check if this is fixed after #32703?

@KevLehman Yes, both drag and drop and selecting multiple files at the same time seems fine, I on 8.2.0-develop rn

Screencast.From.2026-02-19.00-52-17.mp4

Wait if I upload the exact copy / same size of the messages, it uploads only one message @KevLehman

Screencast.From.2026-02-19.01-05-37.mp4

[dodaa08]

Can u check if this is fixed after #32703?

didn't check for the PR that day, but this seems to fix the issue without conflicting.

Screencast.From.2026-02-19.12-04-44.mp4