ERROR: 503 - Service Unavailable

Hi, I have uninstalled openjdk-8-jre because I wanted to install zulu but found out that’s not possible on a 32bit ubuntu system. So I reinstalled openjdk-8-jre again but now I get the error mentioned in the title when opening PaperUI. The BasicUI doesn’t start at all.
The reason why i tried to install zulu was that I suddenly couldn’t edit items any more.
I am running openHAB 2.2.0 Build #1062.
I would be very grateful if somebody could help me to get the system up and running again.
Thanks a lot!

PS. This happened in build #1061, I only updated to #1062 as I thought this could solve the problem. And one more thing. i am using OH2.2 because my xiaomi temp sensor didn’t work at all in 2.1 (and still don’t update in 2.2).