Update errors - LinuxCNC NO_PUBKEY

[stevef]

Never actually installed. I tried from a uspace.deb file.  I get an unmet dependencies error and installation stops.

It might help solving the problem if we know what instructions you were trying to follow.

It looks like something has added LinuxCNC as a source of software updates to your system which has broken the update process.
Click 'Menu' then begin typing 'Software' into the search box.
When you see 'Software & Updates' click on it.

On the window that opens, select the tabs in turn looking for something about LinuxCNC.  It may be in the 'Other Software' tab.
If you find LinuxCNC is checked, uncheck any references to it, then close the window, restart and try updates again.