Cline AI Agent Fix 4 min read

Cline Not Working? Fix API Connection, Model Errors & VS Code Issues

Troubleshoot Cline AI coding agent — API provider errors, model not responding, VS Code extension not loading, context window exceeded, and tool permission issues.

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Common errors and fixes

API provider not configured or key invalid

Cline requires its own API key — it does NOT use your Claude.ai subscription. Configure in Cline settings (gear icon in Cline panel). Supported providers and their key format:

  • Anthropic: sk-ant-api03-... — get at console.anthropic.com
  • OpenAI: sk-...platform.openai.com/api-keys
  • OpenRouter: sk-or-v1-...openrouter.ai/keys — access 200+ models with one key
  • Ollama: http://localhost:11434 as base URL, no API key needed
  • AWS Bedrock / GCP Vertex: requires additional cloud credential setup beyond a simple API key

VS Code extension not loading / extension host crash

  1. 1
    Open VS Code Output panel: View → Output → select "Cline" from the dropdown. Error messages here identify the root cause immediately.
  2. 2
    Extension Host crashed: If the log shows "Extension Host crashed", run "Developer: Reload Window" from the Command Palette (Ctrl+Shift+P) to restart it without closing VS Code.
  3. 3
    Check Node.js is installed: Run node --version in the terminal. Node.js 16 or higher is required for the Cline language server. If missing, install from nodejs.org.
  4. 4
    Workspace trust restriction: If the workspace is "Restricted", Cline is blocked. Click the shield icon in the VS Code status bar and allow Cline access.
  5. 5
    Reinstall as last resort: Uninstall Cline, delete ~/.vscode/extensions/saoudrizwan.claude-dev-* (or %USERPROFILE%\.vscode\extensions\ on Windows), then reinstall from the Extensions panel.

Model not responding / hanging

This usually means the API call is in-flight or timed out. Check the following:

  • Loading indicator visible: Cline may be processing a large file read. Wait up to 60 seconds before assuming a hang.
  • Check API provider status: visit prismix.dev/status for live status of Anthropic, OpenAI, and OpenRouter.
  • Anthropic timeout: claude-3-5-sonnet has a 60s timeout per message in Cline's default config. Large file context can trigger this.
  • Ollama local models: ensure the model is already loaded before using it in Cline — run ollama run model-name first in a terminal.
  • Kill the hung request: click the Stop button (■) in Cline's toolbar to cancel and retry.

Context window / token limit exceeded

Error typically shows as maximum context length exceeded or prompt too long. Approximate context limits by model:

  • claude-3-5-sonnet: 200K tokens — recommended for large codebases
  • gpt-4o: 128K tokens
  • gpt-4o-mini: 128K tokens
  • gemini-1.5-pro: 2M tokens (via OpenRouter)

Actions: the New Task button clears conversation history entirely. Cline's Compact feature summarizes history to free context without losing task state. Avoid @ mentioning large files — ask Cline to read specific line ranges instead.

Permission denied / tool execution errors

Cline uses tools: read_file, write_to_file, execute_command, browser_action, search_files. Common issues:

  • Approval dialog missed: scroll up in the Cline chat — it is waiting for you to click Approve or Deny before continuing.
  • execute_command blocked on Windows: run Set-ExecutionPolicy RemoteSigned -Scope CurrentUser in PowerShell to allow script execution.
  • File write fails on read-only paths: check folder permissions, especially in Program Files or system directories.
  • Auto-approve settings: Cline settings → Allow/Deny → enable "Auto-approve read operations" for smoother workflow on lower-risk actions.

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FAQ

Cline vs Cursor vs GitHub Copilot — when to use Cline?

Cline is an open-source VS Code extension that uses your own API key, giving you full model choice and no subscription lock-in. Cursor is a full IDE fork with its own model infrastructure. Copilot is GitHub's offering with tight GitHub integration. Cline is best when you want model flexibility — use Claude, GPT-4, Gemini, or local models interchangeably.

Does Cline work with local models (Ollama)?

Yes. Set API provider to "Ollama" and base URL to http://localhost:11434. Supported models: any Ollama model, but best results with coding models like deepseek-coder-v2 or qwen2.5-coder. Performance depends on your local hardware.

Cline is too expensive — how to reduce API costs?

Use gpt-4o-mini or claude-3-haiku for simpler tasks (10–50x cheaper than frontier models). Enable Cline's cost tracker to monitor spend. Use OpenRouter to access models pay-as-you-go without a subscription.

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