Error: File has been unexpectedly modified. Read it again before attempting to write it

I have exactly the same issue:

● Read(Controls\Helpers\ControlHelper.cs)
  ⎿  Read 210 lines

● Read(Controls\Helpers\Debouncer.cs)
  ⎿  Read 175 lines

● Read(Controls\Helpers\FileIOHelper.cs)
  ⎿  Read 45 lines

● Read(Controls\Helpers\FilenameHelper.cs)
  ⎿  Read 33 lines

● Update(Controls\Helpers\ControlHelper.cs)
  ⎿  Error: File has been unexpectedly modified. Read it again before attempting to write it.

● Update(Controls\Helpers\Debouncer.cs)
  ⎿  Error: File has been unexpectedly modified. Read it again before attempting to write it.

● Update(Controls\Helpers\FileIOHelper.cs)
  ⎿  Error: File has been unexpectedly modified. Read it again before attempting to write it.

● Update(Controls\Helpers\FilenameHelper.cs)
  ⎿  Error: File has been unexpectedly modified. Read it again before attempting to write it.

Interesting observation. The problem seems not to be in CLI itself, just tried to downgrade to CLI v2.0.53 (this was working yesterday) and then 2.0.52 and 2.0.51 - nothing helps.

Claude's bug report:

Bug Report: Edit Tool Fails with "File unexpectedly modified" immediately after Read

  Environment:
  - Platform: Windows (MSYS_NT-10.0-22631)
  - Claude Code CLI

  Steps to Reproduce:
  1. Read a file using the Read tool
  2. Immediately attempt to edit the same file using the Edit tool
  3. Edit fails with error: "File has been unexpectedly modified. Read it again before attempting to write it."

  Expected Behavior:
  The Edit should succeed since the file was just read and no external modifications occurred between the Read and Edit
  operations.

  Actual Behavior:
  Edit fails claiming the file was modified, even though:
  - No user action modified the file
  - The Read and Edit were consecutive operations
  - The file content in the Edit old_string matches exactly what was returned by Read

  Workaround Attempted:
  - Using sed via Bash tool works, but is not the intended workflow

  Impact:
  This blocks normal file editing workflow entirely, forcing use of shell commands instead.

@claude fix it

Reporting the SAME issue...nothing new to add regarding details but the bugs that are cropping up in Claude Code are making me regret renewing my Max subscription. I left for the downgraded output and performance, only to come back to the same. Lesson is now LEARNED.

Reporting the SAME issue...nothing new to add regarding details but the bugs that are cropping up in Claude Code are making me regret renewing my Max subscription. I left for the downgraded output and performance, only to come back to the same. Lesson is now LEARNED.

It got fixed ages ago. I guess in a few days after. Seems to be a misconfiguration because of some other package updates. But if you got it only now you may try to downgrade CLI till it get work. There are many clones of this report and in some of them were exact versions that worked perfectly.

My current version of CLI (2.0.61) is working well.

I hear you but this volleying between versions approach reintroduces old
bugs that I was glad to see fixed and therefore leaves me to choose how
much I wish to be inconvenienced as opposed to the issue(s) actually being
fixed with a forward momentum vs accepting regressive workarounds.

On Tue, Dec 9, 2025 at 4:01 AM Dimonka2 @.***> wrote:

Dimonka2 left a comment (anthropics/claude-code#12315) <https://github.com/anthropics/claude-code/issues/12315#issuecomment-3631892574> Reporting the SAME issue...nothing new to add regarding details but the bugs that are cropping up in Claude Code are making me regret renewing my Max subscription. I left for the downgraded output and performance, only to come back to the same. Lesson is now LEARNED. It got fixed ages ago. I guess in a few days after. Seems to be a misconfiguration because of some other package updates. But if you got it only now you may try to downgrade CLI till it worked. There are many clones of this report and in some of them were exact versions that worked perfectly. My current version of CLI (2.0.61) is working well. — Reply to this email directly, view it on GitHub <https://github.com/anthropics/claude-code/issues/12315#issuecomment-3631892574>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAQG6WHSYK52UWFYEUTLY634A22YJAVCNFSM6AAAAACNC3MJEOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTMMZRHA4TENJXGQ> . You are receiving this because you commented.Message ID: @.***>

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@claude fix it

i had this issue many times today and yesterday

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

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.