[cesarb]

That's a great start, but does not help if the data was also affected. For instance, running a new version might have upgraded a database to a newer format, or added new data with a format that the older version does not understand.

[forgotpwd16]

True, schema upgrades are an issue which hasn't been discussed[1]. Maybe some kind of versioning or pre-update backup in case of non-invertible data upgrade could help?

[1]: https://discourse.nixos.org/t/automatic-database-schema-upda...