Details on the UHSDR version numbering scheme can be found here.

UHSDR version numbers consists of the parts MAJOR.MINOR.PATCH, e.g.: “2.6.0”.

MAJOR denotes substantial changes in firmware (e.g. very different interface concept, changed hardware). The major number changes seldomly.

MINOR may denote two things: all even minor numbers denote release builds. All odd minor numbers denote development versions. those change frequently.

PATCH denotes the patch level. For released builds (even minor number) the patch level is normally 0, except when bugs have been corrected in the release version instead of issuing a new release. For development releases (odd MINOR number) the patch level changes frequently.

Official UHSDR Releases are archived here.

The most actual UHSDR firmware- and boot loader development versions can be downloaded here.

Github: UHSDR SW repository

These most actual builds are so called “daily builds”, created by the development team for their own use.

• Advantage: these newest versions contain bug fixes and most recent features.
• Disadvantage: “Dailys” may have issues. In this case please temporarilly try older dailys from the archive, or use the official “stable” release (see above).

https://github.com/df8oe/UHSDR/blob/81dd4afae1a52103b2f1824cba34e2ff35e805ea/mchf-eclipse/useful_manuals/bootloader_doc.md