Currently upgrading the history tables to Float64 and using double.sql is mentioned only in 5.0 documentation (in Upgrade notes). The same is true for the "Database history tables upgraded: No" message in the System information section.

This can potentially cause a lot of confusion, so this should be added into known issues also, or some other general page, since the error message will still appear there if you upgrade from 4.0 to 5.2 for example.