## 🐞 Critical Bug Report: Claude Code Unusable Due to Compaction Lockups & `tool_use` 400 Crashes ### Environment * Platform: * [x] Claude CLI (Claude Code) * Claude CLI version: * OS: Windows 11 (via WSL) * Terminal: VS Code Integrated Terminal --- ### ❗ Summary Claude Code is currently **unusable** for long-form or agent-based work due to **two severe, session-breaking bugs**: --- ### 🚫 1. Compaction Lockup (Unrecoverable Timeout) * When ses

Claude Code: Session-Destroying Failures from Compaction Timeouts

Status Fixed / completed

Maintainer reply ✓ Yes — bcherny

Activity 8 comments · opened Jun 21, 2025 · closed Aug 22, 2025

💡 Likely answer: A maintainer (bcherny, collaborator) responded on this thread — see the highlighted reply below.

🐞 Critical Bug Report: Claude Code Unusable Due to Compaction Lockups & `tool_use` 400 Crashes

Environment

Platform:

[x] Claude CLI (Claude Code)
Claude CLI version:
OS: Windows 11 (via WSL)
Terminal: VS Code Integrated Terminal

---

❗ Summary

Claude Code is currently unusable for long-form or agent-based work due to two severe, session-breaking bugs:

---

🚫 1. Compaction Lockup (Unrecoverable Timeout)

When sessions exceed \~2,400 tokens, Claude triggers automatic compaction.
This process retries up to 10 times with:

``API Error (Request timed out.) · Retrying in X seconds… (attempt 1/10 to 10/10)``

After the 10th retry, the session completely freezes.
Manually clearing the session results in:

``404: conversation not found``

All progress is lost. The user must restart the conversation from scratch, breaking all continuity and flow.

---

❌ 2. `tool_use` → `tool_result` Desync (400 Error Crash)

In active coding sessions, Claude may invoke a tool:

``tool_use: toolu_01RF5sCUUx9nbB3zCTHNqvCm``

This fails with a 400 invalid\_request\_error:

``"messages.135:tool_use ids were found without tool_resultblocks immediately after"``

Once this error occurs, the session is permanently broken. Claude cannot continue, and user interaction is blocked.
The only solution is to clear and restart the entire session, losing all context and history.

---

Steps to Reproduce

Compaction Issue:

Start session and interact until token count \~2,400
Wait for auto-compaction
Observe retry loop (10 attempts)
Session becomes unresponsive
Clearing shows 404, session dead

`tool_use` Error:

Claude triggers a tool (e.g., from UI interaction)
Fails to follow with tool_result
CLI returns 400 error
Session must be cleared and restarted

---

Expected Behavior

Compaction should run smoothly or recover gracefully
Every tool_use must be immediately followed by a tool_result
Session context must be preserved — crashes should never require wiping everything

---

Actual Behavior

Compaction stalls → session freezes → unrecoverable 404
tool_use desyncs → 400 error → session permanently crashes
Both require full restart, breaking continuity
Makes Claude Code impossible to use for sustained or structured development

---

Severity

🔥 Critical — Full Session Loss
These bugs completely prevent serious usage. They:

Break long sessions
Block agent workflows
Destroy continuity
Force manual restarts multiple times per day

View original on GitHub ↗

8 Comments

vanman2024 · 1 year ago

Update Todos
⎿ ☒ Diagnose and resolve Claude Code session issues
☒ Test MCP specialists systematically to identify issues
☐ Fix session-intelligence specialist coroutine error in line 308
⎿ API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.53: tool_use ids
were found without tool_result blocks immediately after: toolu_01R83qd4dLX3KxQUS2ADCQrb. Each tool_use
block must have a corresponding tool_result block in the next message."}}

vanman2024 · 1 year ago

Just contirially having issuses with conversations compacting so frustration I hope you fix this ⎿ API Error (Request timed out.) · Retrying in 1 seconds… (attempt 1/10)
⎿ API Error (Request timed out.) · Retrying in 1 seconds… (attempt 2/10)
⎿ API Error (Request timed out.) · Retrying in 2 seconds… (attempt 3/10)

✽ Compacting conversation… (307s · ↓ 363 tokens · esc to interrupt)

vanman2024 · 1 year ago

this is still going ont today just does not seem to consistently compact
⎿ API Error (Request timed out.) · Retrying in 1 seconds… (attempt 1/10)
⎿ API Error (Request timed out.) · Retrying in 1 seconds… (attempt 2/10)
⎿ API Error (Request timed out.) · Retrying in 2 seconds… (attempt 3/10)
⎿ API Error (Connection error.) · Retrying in 4 seconds… (attempt 4/10)
⎿ TypeError (fetch failed)
⎿ API Error (Request timed out.) · Retrying in 8 seconds… (attempt 5/10)
⎿ API Error (Request timed out.) · Retrying in 17 seconds… (attempt 6/10)
⎿ API Error (Request timed out.) · Retrying in 37 seconds… (attempt 7/10)
⎿ API Error (Request timed out.) · Retrying in 33 seconds… (attempt 8/10)

✶ Compacting conversation… (610s · ↓ 442 tokens · esc to interrupt)

thenikso · 1 year ago

I've had this problem for a week. Claude suggested me to try with a different network, indeed going though my phone worked! So I ended up getting a VPN and now it's all smooth. So check if your ISP may be blocking traffic to https://api.anthropic.com/

bcherny collaborator · 1 year ago

Thanks for the report! Both of these are fixed in more recent versions. Please claude update to the latest.

vanman2024 · 1 year ago

Thanks Boris.

________________________________
From: Boris Cherny @.*>
Sent: Friday, August 22, 2025 11:29:57 AM
To: anthropics/claude-code @.*>
Cc: vanman2024 @.>; Author @.>
Subject: Re: [anthropics/claude-code] Claude Code: Session-Destroying Failures from Compaction Timeouts (Issue #2423)

[https://avatars.githubusercontent.com/u/1761758?s=20&v=4]bcherny left a comment (anthropics/claude-code#2423)<https://github.com/anthropics/claude-code/issues/2423#issuecomment-3215253363>

Thanks for the report! Both of these are fixed in more recent versions. Please claude update to the latest.

—
Reply to this email directly, view it on GitHub<https://github.com/anthropics/claude-code/issues/2423#issuecomment-3215253363>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/BLWU4RZQUTGUDKMQRZUMIYD3O5OSLAVCNFSM6AAAAAB72R6YUWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTEMJVGI2TGMZWGM>.
You are receiving this because you authored the thread.Message ID: @.***>

uberspeck · 1 year ago

Looks like this is back...

⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 4 seconds… (attempt 4/10)
⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 10 seconds… (attempt 5/10)
⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 17 seconds… (attempt 6/10)
⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 33 seconds… (attempt 7/10)
⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 39 seconds… (attempt 8/10)
⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 35 seconds… (attempt 9/10)
⎿ API Error (api.anthropic.com | 504: Gateway time-out) · Retrying in 35 seconds… (attempt 10/10)

github-actions[bot] · 11 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.

Claude Code: Session-Destroying Failures from Compaction Timeouts

🐞 Critical Bug Report: Claude Code Unusable Due to Compaction Lockups & tool_use 400 Crashes

Environment

❗ Summary

🚫 1. Compaction Lockup (Unrecoverable Timeout)

❌ 2. tool_use → tool_result Desync (400 Error Crash)

Steps to Reproduce

Compaction Issue:

tool_use Error:

Expected Behavior

Actual Behavior

Severity

8 Comments

Related Claude Code issues

Browse by topic

🐞 Critical Bug Report: Claude Code Unusable Due to Compaction Lockups & `tool_use` 400 Crashes

❌ 2. `tool_use` → `tool_result` Desync (400 Error Crash)

`tool_use` Error: