cowork-dragdrop-issue (Similar to closed #59311 issue)
Preflight Checklist
- [x] I have searched existing issues and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code
What's Wrong?
Drag-and-drop file attachment into a Cowork chat has stopped working. Files no longer attach when dragged from Windows Explorer into the chat window. Attaching via the (+) file picker button still works normally and uploads correctly.
This worked fine until approximately August 21, 2026, and stopped without any local change I'm aware of (no manual app reinstall, no intentional settings change). The app was already on the latest version at the time it broke — updating did not introduce or coincide with a version bump, so this doesn't appear to be a version-to-version regression from a Claude Desktop release; something else changed around that date (possibly a background auto-update component, a Windows update, or third-party software on my machine).
What Should Happen?
The file attaches to the chat and is uploaded into the session's uploads folder, same as when using the (+) picker.
Error Messages/Logs
Steps to Reproduce
- Open a Cowork session in Claude Desktop on Windows 11.
- Drag a file from Windows Explorer over the chat input.
- Drop the file.
Claude Model
Sonnet (default)
Is this a regression?
Yes, this worked in a previous version
Last Working Version
_No response_
Claude Code Version
1.34493.1 (255293)
Platform
Anthropic API
Operating System
Windows
Terminal/Shell
Other
Additional Information
Possibly related to / same root cause as #59311 ("Cowork (Windows 11): drag-and-drop files are not uploaded to the session uploads folder"), which was closed as "not planned." Filing separately because that issue doesn't note a working-then-broke regression, and this one is on the current latest build (1.34493.1) rather than an older version.
This bug happens in the Claude Desktop app's Cowork chat window (a GUI drag-and-drop into the chat input), not in any terminal or shell session.