> For the complete documentation index, see [llms.txt](https://docs.rmhpos.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rmhpos.com/installation/install-central-manager-multi-store/backward-compatibility/about-the-backward-compatibility-extension.md).

# About the Backward Compatibility Extension

If you are using the Flash-based Central Manager, you can use the **Backward Compatibility Extension** to sync data between Central Manager and a mix of Flash and non-Flash stores. You must use the Backward Compatibility Extension if you are gradually upgrading non-Flash stores to Flash.

For non-Flash stores, you must install the Backward Compatibility Extension **on the same computer** where you installed both the Flash-based Central Server app and the non-Flash Central Server app.

After you install the Backward Compatibility Extension and the Central Server app, you must:

* Identify which stores are Flash and which stores are non-Flash.
* Turn off the worksheet processor service on the computer.


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