Update OpenHAB in debian fails (502 bad gateway)

When I do apt update in debian, I get a 502 error:

Err:8 https://dl.bintray.com/openhab/apt-repo2 stable InRelease
  502  Bad Gateway [IP: 34.208.66.129 443]

Is that just temporary? Is there another possibility to update?

Pleas check this