> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/help-center/help-topics/data-api-sdk/realtime-streaming-and-ble/terra-instance-singleton-watch-hang.md).

# Why does my watch streaming session hang?

If a `TerraRT` streaming session hangs and `stopExercise` callbacks never fire, **check whether the `Terra()` instance is being created more than once** (for example, when a watch view is re-instantiated).

* The SDK instance must be used as a **singleton** across the app.
* The SDK does not implement WatchKit's workout configuration delegate, so implement that delegate yourself and call `startExercise` from it.