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

# Why does the sandbox SDK raise CWSandboxAuthenticationError or WandbAuthError?

Which credential the SDK looks for depends on the authentication strategy you select. The SDK doesn't fall back from one strategy to the other.

* **CoreWeave (default)**: reads `CWSANDBOX_API_KEY`, a [CoreWeave API access token](/security/authn-authz/manage-api-access-tokens), and sends it as a bearer token. Requests go out unauthenticated when the variable isn't set.
* **W\&B**: selected explicitly by passing `auth=AuthStrategy.WANDB`. Credential discovery is delegated to the `wandb` library, which accepts an active `wandb login` session, `WANDB_API_KEY`, or the `api.wandb.ai` entry in `~/.netrc`.

Check which credential you have configured, without printing its value:

```bash theme={"system"}
# CoreWeave API access token (the default strategy)
[ -n "$CWSANDBOX_API_KEY" ] && echo "CWSANDBOX_API_KEY is set" || echo "CWSANDBOX_API_KEY is not set"

# W&B API key (requires auth=AuthStrategy.WANDB)
[ -n "$WANDB_API_KEY" ] && echo "WANDB_API_KEY is set" || echo "WANDB_API_KEY is not set"
```

## Common issues

| Issue | Solution |
| - | - |
| No credentials configured | Set `CWSANDBOX_API_KEY`, or set a W\&B credential and pass `auth=AuthStrategy.WANDB` |
| Invalid or expired token | [Create a new API access token](/security/authn-authz/manage-api-access-tokens) from the cloud console |
| W\&B credential set but ignored | Pass `auth=AuthStrategy.WANDB`. The SDK doesn't use a W\&B credential unless you select the strategy |
| `W&B authentication requires the optional wandb dependency` | Install the extra with `uv pip install 'cwsandbox[wandb]'` |
| Sandbox lands in an unexpected entity or project | Set `WANDB_ENTITY` and `WANDB_PROJECT`. Both are optional; W\&B uses your default entity and a `sandbox` project when they're unset |
| Netrc parse errors | Check `~/.netrc` file syntax and permissions |

<Badge stroke shape="pill" color="blue" size="md">[Authentication & Access](/support/sandboxes/tags/authentication-access)</Badge>