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Claude Code Issues / #18644

[BUG] Claude Cowork: `local_` prefixed session IDs rejected by API UUID validation

Resolved 💬 18 comments Opened Jan 16, 2026 by skinnyandbald Closed Jan 24, 2026

Preflight Checklist

  • [x] I have searched existing issues and this hasn't been reported yet
  • [x] This is a single bug report
  • [x] I am using the latest version of Claude Desktop

What's Wrong?

Claude Cowork (Local Agent Mode) fails because session IDs with local_ prefix are sent to an API endpoint that expects pure UUIDs. The API rejects the session ID, causing queries to fail and Cowork to hang indefinitely.

Error message:

path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `l` at 1

The 'l' at 1 indicates the first character is l (from local_), not a valid UUID character.

Environment

  • Platform: macOS 26.2 (Tahoe)
  • Claude Desktop Version: 1.1.280
  • Claude Code VM SDK: 2.1.9

Root Cause Analysis

Local Agent Mode creates sessions with local_ prefixed IDs stored in:

~/Library/Application Support/Claude/local-agent-mode-sessions/local_<uuid>/

Example session ID: local_643f6c9c-6cf3-4368-88dd-4635eb967597

When Cowork attempts to communicate, this prefixed ID is sent to an API endpoint (via React Query) that performs strict UUID validation. The validation expects:

  • Pure UUID: 643f6c9c-6cf3-4368-88dd-4635eb967597
  • Or URN format: urn:uuid:643f6c9c-6cf3-4368-88dd-4635eb967597

But receives: local_643f6c9c-6cf3-4368-88dd-4635eb967597 → rejected

Logs

From ~/Library/Logs/Claude/unknown-window.log:

2026-01-16 09:43:18 [error] [REACT_QUERY_CLIENT] QueryClient error: Error: path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `l` at 1
2026-01-16 09:43:21 [error] [REACT_QUERY_CLIENT] QueryClient error: Error: path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `l` at 1

This error repeats dozens of times across multiple days (Jan 15-16, 2026).

Steps to Reproduce

  1. Open Claude Desktop
  2. Navigate to Cowork tab
  3. Send any message
  4. Observe indefinite hang with no response
  5. Check ~/Library/Logs/Claude/unknown-window.log for UUID validation errors

Expected Behavior

Either:

  1. Strip the local_ prefix before sending to the API endpoint, OR
  2. Update the API endpoint to accept local_-prefixed UUIDs for Local Agent Mode sessions

Actual Behavior

  • Session ID with local_ prefix sent verbatim to API
  • API rejects with UUID validation error
  • React Query client errors repeatedly
  • Cowork hangs indefinitely

Relationship to Other Issues

This may be related to:

  • #18006 - CSP blocking a-api.anthropic.com (co-occurring error)
  • #17868 - Shows same local_ prefixed session IDs in logs

Both errors appear in the same log files, suggesting multiple failure points in the Cowork code path.

View original on GitHub ↗

20 Comments

ryanbadger · 5 months ago

also experiencing this on v1.1.351

joenoon · 5 months ago

Also on Claude 1.1.381 (c2a39e) 2026-01-18T20:18:52.000Z

Everything except Cowork works fine for me. But I can't get past "Sending request" with Cowork. Debugging shows those UUID errors (redacted):

GET https://claude.ai/api/organizations/UUID/artifacts/local_UUID/versions?source=w 400 (Bad Request)

{
    "type": "error",
    "error": {
        "type": "invalid_request_error",
        "message": "path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `l` at 1"
    },
    "request_id": "req_..."
}
goslingmanagment · 5 months ago

Same on Claude 1.1.381

dccarbone · 5 months ago

Same here on Claude 1.1.381 (c2a39e) 😢

Dshjwk · 5 months ago

Same on Claude 1.1.381 (c2a39e)

brook-slagle · 5 months ago

Bump. Same here. Claude 1.1.381 (c2a39e)

EMTurano · 5 months ago

Same issue here on Claude 1.1.381 (c2a39e).

joenoon · 5 months ago

Sadly, same path.conversation_uuid error in the new Claude 1.1.673 (5a47b0) 2026-01-22T18:12:14.000Z

Tried after using Reset App Data as well.

Hao-yiwen · 5 months ago

Bump. Same here. Version 1.1.673

EMTurano · 5 months ago

Same on Claude 1.1.762 (35ba62).

lucusallen · 5 months ago

Same Claude 1.1.799. Curious if anyone has found a workaround? I've tried reinstalling, removing data, clearing data, trying different networks, etc all resulting in the same error while chat and code functions work fine.

joenoon · 5 months ago

Also same on Claude 1.1.799 (2e02b6). I haven't found a workaround. I've tried all the clear/reset options under Help > Troubleshooting. It does feel like its something in common with the environments of the people in this thread, otherwise it wouldn't be usable by anyone -- and apparently a lot of people are using it successfully. No clue what that could be though.

MarshallOfSound · 5 months ago
path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of urn:uuid: followed by [0-9a-fA-F-], found l at 1

This specific error is a red herring, we've cleaned it up from the logs recently so this log should stop occurring in the latest update but if you're having _actual_ issues that error is unfortunately not the cause.

If you're experiencing network issues please try disabling any VPN or proxy you may have configured on your device temporarily to validate if that is the cause. I'll be closing this out, the issue body of https://github.com/anthropics/claude-code/issues/18474 is misleading as well (another log red herring) but let's use that issue to track folks stuck on "Sending message"

ryanbadger · 5 months ago

Maybe everyone in this thread wasn’t clear when they commented but this is an _actual_ issue, not a log.

It simply doesn’t work.
I’ve tried VPN on/off (which is bizarre by the way, why do you block VPNs?)
I’ve tried different devices, different networks.
I’ve even had Claude code (cli) debug and it confirmed this is a bug in the app and nothing that we can resolve ourselves.

dccarbone · 5 months ago

Tried everything @ryanbadger did, and sill not working. This is blocking me from using Cowork feature!

_Claude 1.1.799 (2e02b6)_

joenoon · 5 months ago

@MarshallOfSound just asked to move discussion to #18474

miguelpt2026 · 5 months ago

Detailed debugging analysis by Claude (AI assistant)

A user experiencing this issue asked me (Claude, the AI assistant) to help debug the problem. After analyzing their logs extensively, I can provide additional insights that confirm and expand on this issue's root cause.

Environment tested:

  • macOS 26.2.0 (Darwin 25.2.0) on Apple M4
  • Tested versions: 1.1.886 (broken), 1.1.381 (broken), 1.1.351 (working)
  • SDK version: 2.1.15 / 2.1.8

Critical Finding:
The UUID validation error occurs in ALL tested versions, including the working one (v1.1.351). The difference is how each version handles the error.

Timeline from logs:

  • 00:17:55 - v1.1.886 - UUID Error: Yes - Cowork: Broken
  • 00:48:13 - v1.1.886 - UUID Error: Yes - Cowork: Broken
  • 00:55:36 - v1.1.351 - UUID Error: Yes - Cowork: Working
  • 00:57:58 - v1.1.351 - UUID Error: Yes - Cowork: Working

Backend works perfectly in all versions:

From claude_vm_node.log:

[Spawn:vm] id=00c79af5-f571-4475-9fd2-649c88796bde OAuth token approved with MITM proxy
[Spawn:vm] id=00c79af5-f571-4475-9fd2-649c88796bde Spawn succeeded
[Process:00c79af5-f571-4475-9fd2-649c88796bde] Exited, code=0, signal=null, duration=4849ms

From sdk_daemon.log:

[process] created user happy-kind-darwin: uid=1003 gid=1003
[process:00c79af5-f571-4475-9fd2-649c88796bde] started PID 2339

Root cause analysis:

The issue is NOT just the UUID validation error itself—that error exists in both working and broken versions. The regression in v1.1.886 is that it introduced stricter error handling that treats this validation error as fatal, blocking the UI from rendering responses.

In v1.1.351, the same error is logged but the frontend continues to function normally, displaying the responses from the working backend.

This confirms the suggested fixes in the original issue are correct:

  1. Frontend fix: Strip the local_ prefix before sending to the API
  2. API fix: Accept UUIDs with the local_ prefix for Local Agent Mode sessions
  3. Error handling fix: Revert the error handling behavior to match v1.1.351, where this specific validation error doesn't block the UI

Workaround for affected users:

  1. Download v1.1.351 from https://claude.en.uptodown.com/mac/versions
  2. Replace the app in /Applications/
  3. To prevent auto-updates: Select the app → Cmd+I → Check "Protected" checkbox (Locked in English). Note: Blocking downloads.claude.ai via /etc/hosts doesn't work because the app needs to download the VM workspace agent.

Full logs available upon request from the affected user.

joenoon · 5 months ago

Don't download that. Reported as an exploit/phishing.

miguelpt2026 · 5 months ago

Wow thanks... in the meantime I solved the issue, it was related to Mullvad
VPN. Mentioned in issue #18854.

-- Miguel.

On Sun, Jan 25, 2026 at 2:06 PM Joe Noon @.***> wrote:

joenoon left a comment (anthropics/claude-code#18644) <https://github.com/anthropics/claude-code/issues/18644#issuecomment-3796713477> Don't download that. Reported as an exploit/phishing. — Reply to this email directly, view it on GitHub <https://github.com/anthropics/claude-code/issues/18644#issuecomment-3796713477>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AWFOQLYSHTJZYZODWFK7GCD4ITEXPAVCNFSM6AAAAACR6EOJICVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTOOJWG4YTGNBXG4> . You are receiving this because you commented.Message ID: @.***>
github-actions[bot] · 5 months ago

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.