# Troubleshooting & Common Errors

> Find the right troubleshooting path from the symptom you see in Glow.

Start with what you can see in the run, step, or connected app. This index gives you the first check, then routes you to the focused troubleshooting page.

## Symptom index

  - [It did not start or is still waiting](/reference/workflow-did-not-start-or-is-still-waiting): No run appeared, a webhook seems missing or the run is paused on Wait or Human Review.

- [A value is missing or wrong](/reference/data-and-mapping-problems): A reference stayed literal, a field is empty, the data has the wrong shape or only one list item was processed.

- [A connection or API failed](/reference/connections-and-external-apis): An app reports 401, 403, 429 or a timeout, or an external write may have completed only partly.

- [A Step shows an exact error](/reference/step-error-messages): Look up validation messages from routing, list-processing, loop and Human Review Steps.

  - [The run failed, but the cause is unclear](/reference/debug-a-run): Trace the first unexpected result through the Execution Log, Step executions and upstream data.

## What's Next?

- Read what a single run actually did in the [Execution Log](/build/the-canvas/execution-log).
- Reproduce a failure safely with [Testing & Debugging](/build/the-canvas/testing-and-debugging).
- Design a recovery path with [Error Handling & Retries](/build/core-concepts/error-handling).