> For the complete documentation index, see [llms.txt](https://docs.aurelia.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aurelia.io/developer-guides/error-messages/runtime-html/aur0807.md).

# AUR0807

## Error Message

`AUR0807: Composition has already been activated/deactivated. Id: <controller>`

## Description

`ICompositionController.activate()` was called after that composition controller had already started or stopped. A composition controller represents one composed view and its activation is single-use.

`<au-compose>` serializes structural updates such as `component` and `template` changes, and it owns activation of the composition controller. Model-only updates call `update(model)` directly. Check code that obtains the controller through the `composition` bindable and calls `activate()` directly. That call tries to activate a controller that `<au-compose>` has already activated.

## Solution

Let `<au-compose>` activate the controller. Change `component`, `template`, or `model` to update the composition. Use `composition.update(model)` for an explicit model update.

If standard `<au-compose>` usage produces this error, capture the stack trace and provide a minimal reproduction.


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