: If you encounter a "checksum error" or "corrupt header" message, it often indicates that one of the parts was not downloaded completely or is broken.

[BUG] Keka fails to report broken multipart rar extraction #891 - GitHub

: Start the extraction by opening the first part (.part1.rar) using a tool like WinRAR , 7-Zip , or Keka for macOS.

: You cannot open "part2" on its own. You must have all parts of the archive (e.g., part1, part2, etc.) in the same folder for the extraction to work.