Claude Code: Session-Destroying Failures from Compaction Timeouts

[vanman2024]

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

Environment

• Platform:

  • [x] Claude CLI (Claude Code)

• Claude CLI version: <!-- output of claude --version -->

• OS: Windows 11 (via WSL)

• Terminal: VS Code Integrated Terminal

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❗ Summary

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

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🚫 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.

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❌ 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_result` blocks 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.

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Steps to Reproduce

Compaction Issue:

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

tool_use Error:

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

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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

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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

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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

[vanman2024]

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]

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]

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]

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]

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

[vanman2024]

Thanks Boris.

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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 GitHubhttps://github.com/anthropics/claude-code/issues/2423#issuecomment-3215253363, or unsubscribehttps://github.com/notifications/unsubscribe-auth/BLWU4RZQUTGUDKMQRZUMIYD3O5OSLAVCNFSM6AAAAAB72R6YUWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTEMJVGI2TGMZWGM. You are receiving this because you authored the thread.Message ID: @.***>

[uberspeck]

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]]

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.