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

# Errors and troubleshooting

> Diagnose .NET agent failures, invalid tool data, and interrupted runs.

A failed `RunResult` retains the active step, retry count, request ID, native response ID, provider metadata, and available gateway details.

Check the following first:

* `PHASEO_API_KEY` is available to the process
* tool IDs are unique and stable
* approval decisions use exact tool-call IDs
* paused state is persisted before control leaves the request
* validators do not perform side effects
* cancellation tokens reach dependencies used inside tools

Use lifecycle hooks for application telemetry and DevTools for local run inspection.

## Related

* [Lifecycle hooks](./agent-sdk-lifecycle-hooks)
* [DevTools](./agent-sdk-devtools)