The repository 'https://dl.bintray.com/openhab/apt-repo2 stable Release' is not signed. (Raspberry pi 3)

[marcel_erkel]

This seems to be the problem. Ben is aware.

APT Repo Public Key Expiration & Update

Is there something else going on with the repo tonight? Unfortuantely there is… at the moment, Bintray can’t sign the repository, which is why you get this error. Hopefully this will be fixed when the right person can get to the problem, but if not I will get a workaround to you as soon as I can.