[Bug] File Edit Fails on Windows with Unexpected Modification Error

[kohowski]

Bug Description
all file edits are broken on Windows in Claude Code since v1.0.111 (.110 is the one I have to downgrade to). The error the tool throws every times is:

Update(....)
⎿  Error: File has been unexpectedly modified. Read it again before attempting to write it.

... endless repeat before the model decides to use sed or other workarounds.

no, this is not about mtime. Touching files does not change a thing.

#7443 see how many people have the same issue (ignore the fact the OP decided to close it)

Environment Info

• Platform: win32
• Terminal: windows-terminal
• Version: 1.0.120
• Feedback ID: bce32ccb-ad12-4bf8-b0af-87a694b18f18

Errors

[{"error":"Error: File has been unexpectedly modified. Read it again before attempting to write it.\n    at Object.call (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1902:786)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async VJ5 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:21057)\n    at async WNB (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:17339)\n    at async XJ5 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:16202)\n    at async WJ5 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:15739)\n    at async lO (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:12754)\n    at async lO (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:13667)\n    at async _3 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3421:38227)\n    at async iX (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3421:39182)","timestamp":"2025-09-20T01:04:33.375Z"},{"error":"Error: File has been unexpectedly modified. Read it again before attempting to write it.\n    at Object.call (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1902:786)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async VJ5 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:21057)\n    at async WNB (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:17339)\n    at async XJ5 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:16202)\n    at async WJ5 (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:15739)\n    at async lO (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:12754)\n    at async lO (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:13667)\n    at async lO (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:13667)\n    at async lO (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:3350:13667)","timestamp":"2025-09-20T01:04:57.233Z"},{"error":"Error: Request was aborted.\n    at y51._createMessage (file:///C:/Users/mpotanin/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1000:7955)\n    at processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at runNextTicks (node:internal/process/task_queues:69:3)\n    at listOnTimeout (node:internal/timers:569:9)\n    at process.processTimers (node:internal/timers:543:7)","timestamp":"2025-09-20T01:05:06.388Z"}]

[JosiahSiegel]

#7935

[SShadowS]

It can temporarily be fixed by entering this:
"There's a file modification bug in Claude Code. The workaround is: always use complete absolute Windows paths
with drive letters and backslashes for ALL file operations. Apply this rule going forward, not just for this
file."