How do I repair a corrupt 2Do database on Mac?
If 2Do refuses to launch or behaves erratically, the first step is to restore from a recent automatic backup. On Mac, open 2Do > Settings > Backups, open a known-good backup's ⋯ menu, and choose Restore…. See Backups for the full restore flow, including the backup browser that can pull back individual lists without replacing everything.
If 2Do cannot open far enough to reach Settings, contact support before attempting manual repair. If you can reach the Backups settings later, use Restore from File… to choose a saved backup file directly.
Avoid editing the live database manually unless support asks you to. 2Do uses SQLite alongside companion files, and modifying only one of them can make recovery considerably harder. If restoring from a backup doesn't resolve the issue, please contact support and let us know what was happening just before the problem started.