›_ Claude Code Issues
Claude Code Issues / #18482

[BUG] Conversation compaction intermittently corrupts conversation state: “Compaction failed unexpectedly” and silent prompt submission failures

Resolved 💬 59 comments Opened Jan 16, 2026 by elfieelfieelfie Closed Jan 20, 2026
💡 Likely answer: A maintainer (sid374, contributor) responded on this thread — see the highlighted reply below.

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?

Conversation compaction intermittently fails with the error
"Compaction failed unexpectedly".

After the first compaction event, affected conversations enter a broken state:

  • New prompts fail to execute and revert to draft
  • Prompts with attachments also fail to submit
  • Issue reproduces across iOS, web, and desktop
  • Issue is conversation-specific (other chats may work normally)

This appears to be a backend conversation-state corruption rather than a client-side or rollout issue.

What Should Happen?

Conversation compaction should complete successfully and allow continued prompt execution.

If compaction fails, the conversation should either:

  • Retry safely, or
  • Gracefully recover/reset state without blocking further prompts

Error Messages/Logs

UI error: "Compaction failed unexpectedly"

Observed behavior:
- Prompt submits briefly, then reverts to draft
- No execution occurs
- Occurs after compaction event

Steps to Reproduce

  1. Start a new long-running conversation.
  2. Continue the conversation until automatic compaction triggers.
  3. Observe "Compaction failed unexpectedly".
  4. Attempt to submit a new prompt:
  • Prompt reverts to draft and does not execute.
  1. Attempt to submit a prompt with an attachment:
  • Same failure occurs.
  1. Open the same conversation on iOS, web, and desktop:
  • Issue reproduces across all platforms.
  1. Start a new conversation:
  • New conversation may work normally.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Before Jan 14–15, 2026 (prior to compaction incident)

Claude Code Version

Unknown (issue reproduced across web/iOS/desktop)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

This issue reproduces across platforms:

  • Initially observed on iOS (Claude iOS app)
  • Then reproduced on web and Claude Desktop
  • Same affected conversation fails across all platforms

Behavior:

  • After first automatic compaction event, the conversation enters a broken state
  • Error shown: "Compaction failed unexpectedly"
  • New prompts revert to draft and never execute
  • Prompts with attachments also fail to submit
  • New conversations may work normally

This suggests conversation-level backend state corruption related to the compaction pipeline, not a client or OS-specific issue.

Issue began around the Jan 15, 2026 compaction incident. Community reports indicate similar intermittent failures.

View original on GitHub ↗

59 Comments

github-actions[bot] · 6 months ago

Found 3 possible duplicate issues:

  1. https://github.com/anthropics/claude-code/issues/18211
  2. https://github.com/anthropics/claude-code/issues/18089
  3. https://github.com/anthropics/claude-code/issues/18168

This issue will be automatically closed as a duplicate in 3 days.

  • If your issue is a duplicate, please close it and 👍 the existing issue instead
  • To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

dwight000 · 6 months ago

This is not a duplicate, it is slightly different than the others. From the ticket: "Then reproduced on web and Claude Desktop", there is a fix for Claude code.

dwight000 · 6 months ago

This is still happening 9:43PM EST 1/16/2026. Regarding the error message reported in this ticket, it no longer shows on the UI since a few days ago, but the problem still happens on claude.ai (web) right now, Claude does not accept the message on web. Thinking ON, and Image attachments cause the issue to be reproduced a lot easier.

braidwalkers · 6 months ago

Happening in Claude chat in projects. Web, desktop app, mobile. Can't access project files.

elfieelfieelfie · 6 months ago

Clarifying: the v2.1.11 fix resolves Claude Code (MCP) compaction, but this issue tracks ongoing conversation-state corruption on claude.ai web, Desktop, and mobile (esp. with Thinking ON and image attachments). Multiple users are still reproducing post-fix. This is not resolved.

VibhanshuPandey · 6 months ago

I have the same issue.

binydev · 6 months ago

Frankly speaking, since Jan 14, Claude has disturbed the dev environment. After some chat the it will not work without any UI message , with extended thinking mode. Frankly you need QA!

<img width="1380" height="554" alt="Image" src="https://github.com/user-attachments/assets/bb0c7f5d-8da6-43e1-865c-61bee8bea3a1" />

dwight000 · 6 months ago

There is another variation of this when thinking is off with no errors in any way, and no attachments, sometimes on fresh chats, and does not involve compaction. The prompt appears accepted, nothing happens, then after one minute of nothing happening, you either have to resubmit again and its accepted or the text is removed from accepted reverts to draft in the text box again, and you have to submit yet again and it is accepted.

nilsenist · 5 months ago

Yes, this is a product-breaking issue, which still persists at the time of writing this.

One temporary workaround is to create a new chat within the same project, and to tell Claude to reference the other chat, while continuing in the new one. Of course, the new chat hits the exact same issue after a while, and then another chat has to be created, etc.

This is very disruptive to normal workflow, and it's something Anthropic has to address as soon as possible!

eDubrovsky · 5 months ago

The same issue.

solangerainha · 5 months ago

This has been happening to me as well ever since the major outage on January 14. Several users have reported this and keep reporting it today, 4 days after this problem was flagged as fixed in Claude Status (which is clearly not the case).

A while ago, one of my chats (that I keep having to duplicate in order to continue my work) started kicking messages back into the typing box. I ended up sending the prompt in a file instead and this triggered auto-compact and I can keep using the chat now (until the problem eventually happens again).

There's clearly something wrong that hasn't been addressed yet and the lack of transparency about this is frustrating. Claiming that "all systems are operational" in Claude Status while so many (paying) users are reporting the opposite is incomprehensible.

JURASA · 5 months ago

In launching cowork you deprived the main utility. Excellen vision. Truly. I cannot offer constructive feedback, only that claude code works fine and the web ui has been neuteured - effectively useless

braidwalkers · 5 months ago

Still happening 1/18/26.

Claude chat.
Max plan.
No API.
Affects mobile, web, desktop app.
No access to project files (returns 0 value).
No processes running.
Attachments cause the window to break faster.
Longest text-only token count was 45K. Some have been only 21K before the window becomes unusable.

nizel123 · 5 months ago

In the new Claude update on Android, a bug appeared - when creating an artifact, the window doesn't open during creation... I installed the previous version and it worked
this is also somehow related to this

SysAdminDoc · 5 months ago
In launching cowork you deprived the main utility. Excellen vision. Truly. I cannot offer constructive feedback, only that claude code works fine and the web ui has been neuteured - effectively useless

Glad I'm not the only one who noticed. It's jarring. Just a couple days ago it was a dream, now it's on par with Gemini Pro. And I had just canceled my Gemini Pro plan for Claude Max!

ultraphantom · 5 months ago

I have a similar issue where in a long chat, if I have extended thinking on, I hit submit and it attempts to think, but then it silently fails and reverts back to before I submitted, with no error messages. Turning off extended thinking makes it work again.

momba824 · 5 months ago

I have started creating new chats for each individual issue I'm looking to correct and chat still seems to just pause and not respond with anything after about 5 detailed messages. It make iterating VERY hard and the AI is becoming borderline not usable. I have reset the app, cleared cache, and have tried mobile, web and desktop app.

nizel123 · 5 months ago
I have started creating new chats for each individual issue I'm looking to correct and chat still seems to just pause and not respond with anything after about 5 detailed messages. It make iterating VERY hard and the AI is becoming borderline not usable. I have reset the app, cleared cache, and have tried mobile, web and desktop app.

Just download the previous version cluade via aptoide and it will work for you, it worked for me

luca-teamlab · 5 months ago

Yes...it's very annoying...cannot work today becuase the UI does not work as it should. Paying for the max plan so I would expect to have this fixed as soon as possible

eDubrovsky · 5 months ago

Update: I messaged Boris Cherny on Threads with a link to this issue. He confirmed they're already looking into it. Waiting for updates!

sid374 contributor · 5 months ago

Hey folks, we're looking into this. Just to confirm, you're all seeing this on Claude.ai on web/mobile/desktop right? Or is this Claude Code specific?

momba824 · 5 months ago

I have experienced this in Web/Mobile/ Desktop (tried all 3 to confirm). @sid374

solangerainha · 5 months ago
Hey folks, we're looking into this. Just to confirm, you're all seeing this on Claude.ai on web/mobile/desktop right? Or is this Claude Code specific?

Hi @sid374. Confirmed that Claude.ai web/desktop/mobile (Chat) has been experiencing problems with auto-compact not working since January 15. Thank you for looking into it!

momba824 · 5 months ago

To be clear as well, the issue around non-responsiveness may or may not be tied to the compacting, @sid374 - just want to point out there have been multiple issues reported here.

nizel123 · 5 months ago

"Does this mean that the bug when creating artifacts on Android version 1.260112.27 will finally be fixed? The artifact window just doesn't display or show up when creating, and it's frustrating."

braidwalkers · 5 months ago
Hey folks, we're looking into this. Just to confirm, you're all seeing this on Claude.ai on web/mobile/desktop right? Or is this Claude Code specific?

Correct: Claude.ai (chat) on web/mobile/desktop.

nizel123 · 5 months ago
"Does this mean that the bug when creating artifacts on Android version 1.260112.27 will finally be fixed? The artifact window just doesn't display or show up when creating, and it's frustrating."

I'm tired of using the old version.

ultraphantom · 5 months ago

@sid374 have experienced the issue both in Claude OSX, and the web app.

jdlongmire · 5 months ago

Well, it’s good to see I’m not crazy. At least on this, anyway - I downgraded my service until this gets fixed.

davidwholesale · 5 months ago

I started experiencing this bug today.

I am running Claude on Windows 11, I have also tested on Mac with the same issue. I have tried mobile app, desktop app, and Chrome browser.

I even opened a new chat and after roughly 10 short messages, I experienced the same error. Extended thinking has no chance of success, but occasionally, when I type one short sentence in the old or new chats, the issue is briefly resolved; upon the next message, it reverts back to having issues.

ecaudetg-droid · 5 months ago

Same thing here - very annoying. Happens on web and macOS app.

OniiTale · 5 months ago

The same thing is still happening. I started having this issue two days ago and have tried different browsers as well as the app, but it still doesn’t work.

austinxduong · 5 months ago

Glad I found this thread. Started experience this similar bug 2 days ago (except no error message), specifically on Claude Desktop. Last night, I submitted a support ticket thinking it was just me. Just after a few prompts (not lasting an entire daily session)-- at random, Claude Desktop will "think" with the flashing icon, then my prompt will also kick back into the chat box, and Claude sends no response back (with no error message). Current workaround is to start a new chat session, which is getting to a point where its not a feasible workflow, as I'd have to re-provide full context of the previous working session, where I was in the middle of a complex debugging session, or in the middle of a large architectural implementation.

shirba17 · 5 months ago

Yes, I'm having the same issue since 3 days ago. I have a long-running conversation containing a lot of design and scope decisions and context that was working perfectly until then. Now, similar to @austinxduong Claude Desktop (running on Mac) will "think" with the flashing icon, then my prompt will also kick back into the chat box, and Claude sends no response back (with no error message). Super frustrating. Starting a new conversation seems like an unreliable option as I'm dubious it can keep track of my scope and context - and super cumbersome to have to 'remind' it or refer back to the original conversation constantly. I basically can't continue working on my project until this is fixed. Any idea how long this will take to fix and, once fixed, if it's likely that I'll be able to resume my original conversation? And can anyone recommend a resource link on how to prepare to migrate to a different platform if this persists? I find it frustrating that there is no official communication coming from Anthropic API (that I know of) - how are we to know a.) what's going on, b.) what their progress is and c.) when they expect it to be fixed?

ultraphantom · 5 months ago

when is this going to be fixed? Paying for max plan and Claude becomes unusable in extended thinking mode, after the chat grows in length. Have to start over and re-explain all context

Shyhots · 5 months ago

Same problem. Long conversation, message gets sent back, compaction doesn't happen.

nomad1013 · 5 months ago

Same issues on my end as well! Tried all the troubleshooting methods possible and I suspect it's the compacting fix they implemented because to be honest I don't see the chat doing that anymore and it just spits my prompt right back at me. I had some success removing my chats from my projects and a few messages worked and then same thing started to happen. Completely unacceptable to go two days like this already and pay this amount of money man.

dragilderart-cell · 5 months ago

Claude just updated his status to say they're investigating a bug; hopefully that's it and we'll have a solution soon.

entropyharvest · 5 months ago

Summary

Every conversation I start dies after 50-100 messages when compaction triggers. The message_store_sync_loss error fires, and the conversation becomes permanently write-locked (can view/regenerate but cannot send new messages). This happens on both claude.ai web and Claude Desktop.

I'm using Claude exactly as intended: projects with reference documents, tool use, working sessions longer than a few messages. The product is broken for its primary use case.

Evidence: 30+ sync_loss events in 9 days

From my Claude Desktop logs (same behavior on web):

Jan 12 13:13 - Invalid UUID error → message_store_sync_loss
Jan 12 13:33 - Overloaded (10+ retries) → message_store_sync_loss
Jan 12 13:41 - Overloaded → message_store_sync_loss
Jan 12 13:53 - Overloaded → message_store_sync_loss
Jan 12 14:25 - message_store_sync_loss
Jan 12 16:04 - Network error → "Failed all attempts to invalidate conversation tree" → message_store_sync_loss
Jan 15 12:22-12:25 - 7 consecutive "Internal server error" → message_store_sync_loss after each
Jan 16 08:34 - 3x Internal server error → message_store_sync_loss
Jan 16 08:41 - Internal server error → message_store_sync_loss
Jan 16 09:03-09:15 - 7x Internal server error → message_store_sync_loss
Jan 16 11:21-11:45 - 5x Internal server error → message_store_sync_loss
Jan 16 16:24 - Network error → "Failed all attempts to invalidate conversation tree" → message_store_sync_loss
Jan 16 17:08-17:09 - 3x Internal server error → message_store_sync_loss
Jan 20 10:35 - Internal server error → message_store_sync_loss
Jan 20 10:51 - 2x Internal server error → message_store_sync_loss

The Pattern

Every message_store_sync_loss is preceded by one of:

  1. Internal server error (marked "Not retryable error, throwing")
  2. Overloaded (after exhausting retries)
  3. Network error → "Failed all attempts to invalidate conversation tree"

The server fails, and then conversation state is permanently corrupted. The client detects the mismatch but cannot recover.

Timeline

  • Jan 12: First sync_loss events in my logs - this predates the Jan 15 incident
  • Jan 15 07:28 UTC: Anthropic posts "Compaction is having issues"
  • Jan 15 12:22-12:25: 7 sync_loss events in 3 minutes on my account
  • Jan 15 17:02 UTC: Anthropic marks incident "Resolved"
  • Jan 16 and onward: Sync_loss events continue at same or higher rate
  • Jan 20: Still happening. Every conversation dies.

The Jan 15 "fix" did not fix this.

Impact

  • Every conversation breaks after first or second compaction
  • Cannot use Claude for any sustained work
  • Paying for Pro subscription for a service that is unusable
  • This is not edge case usage - projects, tools, and longer sessions are core advertised features

Environment

  • Reproduces on claude.ai (web, Firefox and Edge)
  • Reproduces on Claude Desktop (Windows, latest version)
  • Same behavior across multiple conversations and projects

Full logs attached: claude-desktop-logs-2026.txt

claude-desktop-logs-2026.txt

nizel123 · 5 months ago

When will there be a new update with fixes in android version?

3 days in version 1.260119.17 in google play with bug When creating an artifact document, the window doesn't open and it's annoying. I'm still on version 1.251215.57 via aptoide and this is annoying, why can't the troubleshooters fix this stupid bug?

rboyce-ant contributor · 5 months ago

Hi all, just for clarification, this repo is intended for tracking issues in Claude Code, not the claude.ai website. If you're still having issues with compaction in Claude Code after v2.1.11, please file an issue and I'll look into it! I've also let the claude.ai team know about the issues with compaction in conversations.

elfieelfieelfie · 5 months ago

This issue is now being tracked in #18866 (same claude.ai web/desktop/mobile compaction bug). Please follow that thread for updates

Stig2204 · 5 months ago

enntre temps sur le site, ils disent qu'il n'ya pas d'issues <img width="1017" height="1405" alt="Image" src="https://github.com/user-attachments/assets/76eef493-48ec-4f9f-8499-320d1ff13360" />

Ijelale · 5 months ago

I do have an issue with Claude Cowork on Mac App. the workspace fails to start, run debug with my IT team no VPN or firewall issue.

EMAnderson0723 · 5 months ago

I am having this exact issue as well.

elfieelfieelfie · 5 months ago

Update: This issue is now being tracked in a new, focused report that isolates the remaining post–Jan 15 failure mode: 👉 #20696

Please follow that thread for updates. This thread was closed due to mixed scope.
nizel123 · 5 months ago

I can't stand it anymore... I waited and waited for this bug on Android to be fixed... I realize I've written about this many times. It was at the beginning of the week, I was specifically waiting to check. And in the end, they're idiots... I don't understand this anymore. Is this a bug or is there a final solution for Android versions?! It's inconvenient! And it's so annoying that I can't even complain to the developers... there's only fin bot! I don't know, just tell me yourself if this is a bug or not? Or are the developers just idiots and we just have to live with it?

nizel123 · 5 months ago

In new versions of Android, they removed the ability to view document creation and now you have to view it manually. The developers are idiots, idiots, and deer.

nizel123 · 5 months ago

I'm already sick of it... How much longer can this go on!? Why isn't this mentioned?! That they disable this feature when creating an artifact?! I've had enough! Enough!

hirako2000 · 5 months ago
they're idiots

I don't think calling developers idiots is polite. It's also not useful, and inaccurate.

The dupe bug explained that they released multiple fixes across the products. If you read the thread you will understand compaction now happens seamlessly, and under the hood.

Did it fix the problem ? Not really, but it is a reasonable fix since the design of compacting an immense context is likely going over the context itself. So just in time rather than when too late compaction is _fair_ to consider idiocy far from the logic applied to resolve the reported issue, and thus closing them both.

momba824 · 5 months ago
I'm already sick of it... How much longer can this go on!? Why isn't this mentioned?! That they disable this feature when creating an artifact?! I've had enough! Enough!

There are some workarounds that you can use if you you’re getting stuck. One of the major ones is to just work through one issue at a time, produce a project state when you’re done and using it to have a reference for the new chat. The other one is a manual compact command. It’s a complex issues I’m sure.

chuck146 · 5 months ago

Having the same issue here

reda2407 · 5 months ago

05/02/2026, still open, ans has been since January 2026

meanwater · 5 months ago

same issue

bluedasher13 · 5 months ago

Same issue today.

<img width="318" height="85" alt="Image" src="https://github.com/user-attachments/assets/3702e01d-b2be-4959-a7c9-0da7bc07116e" />

<img width="935" height="266" alt="Image" src="https://github.com/user-attachments/assets/76377548-97b2-43de-ac64-37dd8ae2f393" />

GeorgeRichardMorton · 5 months ago

same issue here

gonewx · 4 months ago

This has been my #1 pain point. Lost a 3-hour debugging session last week because compaction silently dropped the context where I'd narrowed down a race condition to a specific code path.

As a workaround, I've been using Mantra to automatically snapshot my sessions before compaction kicks in. It watches the JSONL files and creates restore points, so when compaction mangles things, I can roll back to the pre-compaction state and continue from there.

Not a fix for the root cause obviously, but it's saved me from re-explaining complex context multiple times now. Would love to see the core compaction logic improved so tools like this become unnecessary.

gonewx · 4 months ago

This has been my #1 pain point. Lost a 3-hour debugging session last week because compaction silently dropped the context where I'd narrowed down a race condition to a specific code path.

As a workaround, I've been using Mantra to automatically snapshot my sessions before compaction kicks in. It watches the JSONL files and creates restore points, so when compaction mangles things, I can roll back to the pre-compaction state and continue from there.

Not a fix for the root cause obviously, but it's saved me from re-explaining complex context multiple times now.

github-actions[bot] · 4 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.