[BUG] Claude Desktop: 20 Session Resets in 10 Days - Server-Side API Failures Cascade to Session Destruction

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?

Note: This is a Claude Desktop issue, not Claude Code. Filing here because no Claude Desktop issue tracker exists.

Claude Desktop sessions are being destroyed when Anthropic's API completion endpoint returns errors (timeouts, 500s, network errors). The client fails to gracefully handle these errors and instead cascades into session corruption.

20 documented incidents in 10 days (Jan 6-15, 2026)

Error cascade pattern (all 20 incidents follow this):

1. API returns error (timeout / overloaded / internal server error / network error)
2. Client logs message_store_sync_loss
3. Client attempts conversation tree invalidation (fails)
4. Session destroyed - "This conversation could not be found"

Tonight's incidents (Jan 15):

• 22:15 CST: 4 consecutive Internal server errors over 56 seconds
• 23:30 CST: Network error → instant cascade to session destruction

Additional bug: Logs show repeated CSP violations for https://a-api.anthropic.com/v1/m - the client is trying to reach endpoints not whitelisted in its own Content Security Policy.

What Should Happen?

1. When API returns transient errors (timeout, 500, network error), client should retry gracefully without corrupting local state
2. If recovery fails, client should preserve conversation history and allow user to resume
3. User should never see "This conversation could not be found" for an active session
4. CSP configuration should include all endpoints the client needs to reach

Error Messages/Logs

From claude.ai-web.log (Jan 15, 2026):

# Incident #19 - 22:15 CST (4 consecutive 500s)
2026-01-15 22:15:10 [error] [COMPLETION] Request failed Error: Internal server error
2026-01-15 22:15:10 [error] [COMPLETION] Not retryable error, throwing
2026-01-15 22:15:10 [warn] [COMPLETION] message_store_sync_loss [object Object]
2026-01-15 22:15:29 [error] [COMPLETION] Request failed Error: Internal server error
2026-01-15 22:15:35 [error] [COMPLETION] Request failed Error: Internal server error
2026-01-15 22:16:06 [error] [COMPLETION] Request failed Error: Internal server error
2026-01-15 22:16:20 [error] [REACT_QUERY_CLIENT] QueryClient error: This conversation could not be found

# Incident #20 - 23:30 CST (network error)
2026-01-15 23:30:00 [error] [COMPLETION] Request failed TypeError: network error
2026-01-15 23:30:00 [error] [COMPLETION] Non-API stream error TypeError: network error
2026-01-15 23:30:00 [warn] [COMPLETION] message_store_sync_loss [object Object]
2026-01-15 23:30:02 [error] [COMPLETION] Failed all attempts to invalidate conversation tree with consistency=eventual

# CSP Violations (throughout day)
2026-01-15 14:36:48 [error] Refused to connect to 'https://a-api.anthropic.com/v1/m' because it violates the following Content Security Policy directive

Steps to Reproduce

a1. Open Claude Desktop with MCP server enabled (Desktop Commander in my case)

1. Start an extended conversation with multiple tool calls
2. 3. Continue working until an API timeout, overload, or internal server error occurs
3. 4. Observe the error cascade in logs:
4. - [COMPLETION] Request failed Error: Internal server error (or timeout/overloaded)
5. - [COMPLETION] message_store_sync_loss
6. - Failed all attempts to invalidate conversation tree
7. 5. Session is destroyed - "This conversation could not be found"

Trigger conditions (increase likelihood):

• Longer conversations (more context)
• - Multiple sequential tool calls
• - - High-traffic periods (more server errors)
• - - - Evening hours seem worse in my experience

Frequency: 20 incidents in 10 days (Jan 6-15, 2026)

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A - Claude Desktop (latest), no dedicated issue tracker

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_