> 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/ui-virtualization/aur6003.md).

# AUR6003

## Error Message

`AUR6003: Scroller info is readonly and cannot be modified.`

## Description

This error occurs when code attempts to mutate scroller information that the virtualization system treats as readonly (internal state used for measurement and scheduling).

## Example Trigger

This is most commonly triggered by directly modifying internal virtualization/scroller state from custom code or a custom integration.

## Correct Usage

* Treat virtualization internals as readonly.
* Use public APIs/configuration options (or supported extension points) instead of mutating internal scroller info objects.

## Troubleshooting

* Search for code that assigns to scroller/virtual-repeat internal properties (for example in custom strategies or wrappers).
* If you need custom behavior, prefer implementing a supported strategy/adapter rather than mutating internal state.


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