# Export / Synchronization Process

If you’re exporting a new Revit project, its data will be collected from the revit model, analyzed, converted to the Web App Building Project format and uploaded to the server according to the selected scope. The newly created Web App building project will receive a version number **1**.

<figure><img src="/files/G3G0sV98MMwBOuUt2DXa" alt=""><figcaption></figcaption></figure>

If you’re updating the existing building project, the plugin will collect all required data from the current Revit project, compare it to the selected building project and create a patch containing only the data that was changed on the Revit side (additional instances and materials, changed quantities, etc.) Then this patch will be applied to the existing building project.

* Material refinements made on Web App will be preserved and the corresponding element masses recalculated using the new densities. New building elements and materials which were added on Web App will be retained as well as automatically added reinforcements. If the existing building element quantities or names were changed both in the Web App and Revit projects, the Revit changes will be prioritized.
* During an update, the **Export Detail**, **Project Location** and **Web App's Project Name** settings will be taken from the existing bimCAT building project, so the user won’t be able to change them from the plugin. **Floors** and **Height** values will be also taken from Web App, as they were automatically calculated during the initial export and it’s highly likely the user would want to refine them.
* During an update, the new supported Revit model categories selected in the **Manage Scope > Manage Categories** dialog will be added to the building project.
* During an update, the supported Revit model categories unselected in the **Manage Scope > Manage Categories** dialog will be removed from the bimCAT building project together with all their building elements.
* During every synchronization the plugin will check if the Revit project was changed since the last export. If yes, the version number will be automatically incremented by 1. If not, it will stay the same.

  <figure><img src="/files/NORg3DiJ0eIDJf4imV4j" alt=""><figcaption></figcaption></figure>
* After an update, the building project ID and URL will remain the same.

See more details in the **Project update example** section below.

The export progress and what exactly is currently happening will be shown in the special progress window.

<div align="left"><figure><img src="/files/0JmZIk9tEQGseqkWMZbs" alt=""><figcaption></figcaption></figure></div>

You may cancel the process at any moment by either clicking the Cancel button or closing this window.

If error 503 (service not available) occurs during the export process, the plugin will attempt to automatically reconnect three times in 10, 20 and 60 seconds.

If all the reconnection attempts fail or other critical error occurs, the export process will stop and the error dialog will be displayed.

<div align="left"><figure><img src="/files/GBwEbwd6fRenLeBZhlKf" alt=""><figcaption></figcaption></figure></div>

More detailed information could be retrieved from the **error log** created by the plugin.


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