> ## Documentation Index
> Fetch the complete documentation index at: https://manifest.build/llm-gateway/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# M100: Provider API key missing

> M100 is returned when routing selects a provider for which the harness has no API key.

## What you saw

```text theme={"theme":{"light":"github-light","dark":"github-dark"}}
[🦚 Manifest M100] No anthropic API key yet. Add one here: https://app.manifest.build/...
See https://manifest.build/llm-gateway/docs/errors/M100
```

The provider name (`anthropic` in the example) varies based on which provider the gateway selected.

## Why it happened

Routing picked a provider that has no key on file for this harness. The gateway won't silently swap vendors on you, so the request stops here.

## How to fix it

1. Open the dashboard link in the error message. It goes straight to the harness's **Routing** page.
2. Open **Providers → Usage-based** in the sidebar and add a key for the named provider. Or remove that provider from your tier configuration so routing won't pick it again.
3. Retry the request.

## Related

* [M101: No providers configured](/llm-gateway/docs/llm-gateway/docs/errors/M101)
* [M102: Provider subscription credentials unusable](/llm-gateway/docs/llm-gateway/docs/errors/M102)
* [M003: Invalid key format](/llm-gateway/docs/llm-gateway/docs/errors/M003)
* [Routing](/llm-gateway/docs/llm-gateway/docs/llm-gateway)
* [API key providers](/llm-gateway/docs/llm-gateway/docs/providers/api-key-providers)
* [Subscription-based providers](/llm-gateway/docs/llm-gateway/docs/providers/subscription-based-providers)
* [All error codes](/llm-gateway/docs/llm-gateway/docs/errors)