How to Fix OpenClaw Unknown Model Error

The Error

If you're seeing this error in your OpenClaw logs, you're not alone:

This error stops OpenClaw dead in its tracks. The agent crashes before it can even respond to your message. Frustrating? Absolutely. But the fix is straightforward once you understand what's happening.

Understanding the Root Cause

OpenClaw fails hard if the model ID is not valid for the provider. Unlike some systems that gracefully fall back to a default, OpenClaw requires exact, versioned model identifiers.

GitHub Context

This is a known issue in the OpenClaw community:

• Issue #4179: "Model selection lacks validation - allows non-existent models causing agent crashes"
• Discussion #5991: Multiple users reporting the exact same error with various model aliases

The maintainers are aware of the validation gap, but until it's fixed upstream, you need to manually ensure your config uses valid IDs.

Step-by-Step Fix

1Locate the Config File

OpenClaw stores its configuration at a default path:

Verify the file exists:

You should see output confirming the file exists. If not, OpenClaw may not be properly initialized.

2Correct the Model Configuration

Open the config file for editing:

Find the agents.defaults.model section and update it to use a valid versioned Anthropic model ID:

After editing, save the file:

• Press CTRL + O to write the file
• Press Enter to confirm
• Press CTRL + X to exit nano

3(Optional) Allow Multiple Models

If you want to dynamically switch between models, you can configure an allowlist:

This is optional. If you're only using one model, skip this step.

4Safely Stop OpenClaw

Here's the tricky part: OpenClaw runs as a parent process with child gateway processes. If you only kill one PID, the parent respawns the child. You need to kill the parent first.

Find all running OpenClaw processes:

You'll see output like:

Identify the parent PID:

The PPID column shows the parent process ID.

Stop the parent process:

Clean up any remaining children:

Confirm OpenClaw is fully stopped:

You should see "fully stopped" if no processes remain.

5Restart OpenClaw

Start OpenClaw again with your normal command:

(Or whatever command you typically use to start OpenClaw.)

6Verify Model Loaded

Check that the correct model is now loaded:

Expected output:

If you see your configured model ID, you're good to go!

7Confirm Error Is Gone

Monitor the logs in real-time:

You should not see the Unknown model error anymore. Test by sending a message to your agent.

8If Error Returns

If the error reappears after following all steps, check for environment variable overrides:

If you see any variables setting model IDs (like ANTHROPIC_MODEL), they might be overriding your config. Unset them or correct their values.

Summary

Valid Anthropic Model IDs (2026)

Here are the current valid model IDs you can use with OpenClaw and Anthropic:

• anthropic/claude-sonnet-4-5-20250929 — Recommended Sonnet model (balanced performance)
• anthropic/claude-opus-4-5 — Highest quality Opus model (best reasoning)
• anthropic/claude-haiku-4 — Fastest Haiku model (quick responses)

Always include the anthropic/ prefix and the full version suffix. Check the Anthropic documentation for the latest model releases.

Related Resources

• Complete OpenClaw Setup Guide — Full installation walkthrough
• Vibe Coding Fundamentals — Learn the 5 essential AI coding skills
• OpenClaw GitHub Repository — Official source code and issues