> For the complete documentation index, see [llms.txt](https://docs.buzzy.buzz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.buzzy.buzz/troubleshooting/app-and-runtime-issues.md).

# App and Runtime Issues

Troubleshoot previewed and published Buzzy app errors, blank screens, missing screens, broken bindings, and runtime exceptions.

Runtime issues happen when an app is previewed, tested, or opened by a user. They are usually caused by missing or mismatched app configuration, data context, app actions, or custom runtime code.

## Common Symptoms

* app URL opens but shows a named error
* preview or published app shows a blank screen
* navigation opens the wrong screen or cannot find the screen
* view, form, filter, or field cannot find its datatable or field
* action fails or does not pass the current row
* Code Widget, Function, or runtime action throws an exception

## Start With Error Codes

If the app shows a named error, go to [App Error Codes](/troubleshooting/app-error-codes.md). Error codes are grouped into:

* app and route errors
* datatable and field errors
* component and action errors
* runtime exceptions

## Fast Triage

1. Open the app from the Dashboard to rule out stale URLs.
2. Check what changed recently: deleted screens, renamed fields, regenerated data model, Figma publish, new action, new widget, or new function.
3. Open the affected screen in the editor.
4. Use [In-App Debugging](/troubleshooting/in-app-debugging.md) to inspect screen context, selected node, bindings, actions, fields, display formulas, and runtime row data.
5. Check whether a detail or edit screen expects the previous action to pass the current row.
6. After fixing the issue, preview again and rerun relevant [Tests](/the-building-blocks/release-tests.md).

## Related Guides

* [App Error Codes](/troubleshooting/app-error-codes.md)
* [In-App Debugging](/troubleshooting/in-app-debugging.md)
* [Tests](/the-building-blocks/release-tests.md)
* [Integration Issues](/troubleshooting/integration-issues.md)