Gramps is a genealogy program that is both intuitive for hobbyists and feature-complete for professional genealogists.
Gramps Database Changes: Version 5.0 and later of Gramps may not be able to import data from version 3.x automatically. If you upgraded from a previous version of Gramps, your old version was copied to a GrampsPortableLegacy directory alongside your upgraded one. You can open that version and export to Gramps XML format, then create a new family tree in Gramps 5.1 and import your data if you encounter issues.