Claude Code CLI Unusable: APIErrorterminated + Offline Flickering + Extreme Execution Delays

Environment

• Platform (select one):

• [x] Claude Code
• [ ] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: claude --version → claude-code v0.2.8
• Operating System: Windows 11 Pro (via WSL2 Ubuntu 22.04)
• Terminal: VS Code integrated terminal and Windows Terminal

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Bug Description

Claude Code frequently stalls on basic prompts. The CLI flashes the error:

APIErrorterminated… (113s · ↓ 1 tokens · esc to interrupt)

and flickers “offline” repeatedly. Execution eventually completes after 1–2+ minutes, but responses are often partial, extremely slow, or limited to just a few tokens. This significantly disrupts usage and productivity.

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Steps to Reproduce

1. Start Claude Code via CLI in WSL
2. Enter any prompt (e.g., “Write a Python script to parse a CSV file”)
3. Wait 60–120+ seconds
4. Watch for:

• APIErrorterminated message
• “Offline” flickering status
• Delayed output (usually 1–5 tokens at first)
• Completion after excessive wait time

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Expected Behavior

• Claude should respond within seconds
• Full prompt should execute smoothly
• Terminal should not flicker or show API errors

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Actual Behavior

• Long delays (1–2+ minutes per prompt)
• APIErrorterminated appears almost every time
• “Offline” status flashes repeatedly
• Responses eventually return, but often very limited or delayed

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Additional Context

• Issue is present across multiple sessions and terminals
• Internet is stable and system resources are not maxed out
• CLI is unusable for productive work due to the lag
• Began worsening mid-June 2025