Hello Tom,
Thanks for trying out Prime Mover. This error could be caused by different factors that could be hosting-related, connection interruption or a multisite under maintenance mode (e.g. updating plugins). Fatal error can also cause this error.
To help us understand the true origin of this error, can you please provide more details on your issue by following this troubleshooting guidelines. Please describe the steps that results to this error. Once you followed the guidelines with WP_DEBUG enabled, we will know this error better and we can possibly fix it.
Also does this happen during export? or import?
If these happens during export, can you try exporting database only and see what happens? If exporting database works but does not work with export media files or with plugins, your site might be too heavy for your current hosting setup.
In this case, you can try to break down the export into different stages, you can read more tips here. Thanks again !
