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Has anyone ever successfully moved a working ERPNext system to another server without using a server image?

I suggest to use LXD containers and so snapshot / backup / movement is as easy as moving zip files. Snapshot can even be set to auto expire - so you can setup a frequency and old ones get deleted. Inside LXD container you can install erpnext in traditional way. It does not require much extra knowledge of terminology - little setup to forward incoming port 80/443 traffic to container. Let me know if interested - I can share few links.