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[BUG] Edit tool fails with "File has been unexpectedly modified" when file hasn't changed (Windows) #17684
Closed as duplicate
Description
Preflight Checklist
- I have searched existing issues and this hasn't been reported yet
- This is a single bug report (please file separate reports for different bugs)
- I am using the latest version of Claude Code
What's Wrong?
Description:
The Edit tool consistently fails with the error "File has been unexpectedly modified. Read it again before attempting to write it." even when:
- No editors are open
- No dev servers or file watchers running
- No manual edits being made
- File timestamp remains unchanged between Read and Edit calls
The issue accumulates over a session and temporarily resolves after restarting the PC.
Environment:
- OS: Windows 11
- Claude Code version: Latest (installed via npm)
- Node.js version: 18+
- Working directory: C:\Users[username]
- Target files: D:\Work[project] (different drive)
Observed Behavior:
● Read(D:\Work\project\src\file.ts)
⎿ Error reading file
● # Read succeeds
Read file D:/Work/project/src/file.ts
# Immediate Edit fails
Edit tool error: "File has been unexpectedly modified. Read it again before attempting to write it."
# Verify file wasn't modified
$ stat file.ts | grep Modify
Modify: 2026-01-12 04:04:01.268346800 -0800 # Timestamp unchanged
Verification that file is stable:
# File timestamp doesn't change on its own
$ stat file.ts | grep Modify
Modify: 2026-01-12 04:04:01.268346800 -0800
$ sleep 5
$ stat file.ts | grep Modify
Modify: 2026-01-12 04:04:01.268346800 -0800 # Same
Additional observations:
- Happens on ALL files after the bug starts occurring (tested .ts, .tsx, .json files)
- sed commands via Bash tool work fine as a workaround
- The Write tool (full file replacement) may also work
- Cross-drive scenario: Working directory on C:, files on D: drive
- Restarting PC temporarily fixes the issue
- Issue returns after ~30-60 minutes of usage
Expected Behavior:
Edit tool should succeed when the file hasn't been modified between Read and Edit calls.
Workarounds:
- Use sed via Bash tool for edits
- Restart Claude Code / PC
- Provide full file content for manual pasting
Possible Causes:
- File hash/checksum tracking getting corrupted over time
- Windows NTFS timestamp precision issues
- Cross-drive path handling issues
- Memory/state leak in file tracking
### What Should Happen?
Edit tool should succeed when the file hasn't been modified between Read and Edit calls.
### Error Messages/Logs
```shell
Error: File has been unexpectedly modified. Read it again before attempting to write it.
Steps to Reproduce
- Use Claude Code for an extended session (30+ minutes)
- Read a file using the Read tool
- Immediately attempt to Edit the same file
- Error occurs even with no external modifications
Claude Model
Opus
Is this a regression?
I don't know
Last Working Version
No response
Claude Code Version
2.1.5 (Claude Code)
Platform
Anthropic API
Operating System
Windows
Terminal/Shell
IntelliJ IDEA terminal
Additional Information
tried it also on powershell terminal same thing
Activity
github-actions commentedon Jan 12, 2026
Found 3 possible duplicate issues:
This issue will be automatically closed as a duplicate in 3 days.
🤖 Generated with Claude Code
github-actions commentedon Jan 16, 2026
This issue has been automatically closed as a duplicate of #12695.
If this is incorrect, please re-open this issue or create a new one.
🤖 Generated with Claude Code
github-actions commentedon Jan 24, 2026
This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.