[SOLVED] OH2.1 PaperUI not accepting changes

I upgraded my testbed fro OH2.0 to 2.1. Not sure why, but it broke completely. So I descided to start from scratch.
Uninstalled everything and started over. All seems to work fine until I recognized that I cant add any Binding configs from PaperUI > Inbox > + Sign.
Tried for zwave, Exec and Tankerkoenig. On pressing save, all are failing with error message “ERROR 504 - Gateway Time-out”.
I turned on DEBUG logging and found those lines:

2017-06-29 15:45:15.070 [DEBUG] [org.eclipse.jetty.io.IdleTimeout    ] - SelectChannelEndPoint@f62a9a9{/127.0.0.1:39909<->8080,Open,in,out,-,-,7023/30000,HttpConnection}{io=0,kio=0,kro=1} idle timeout check, elapsed: 7023 ms, remaining: 22977 ms
2017-06-29 15:45:15.650 [DEBUG] [rg.quartz.core.QuartzSchedulerThread] - batch acquisition of 0 triggers
2017-06-29 15:45:15.650 [DEBUG] [org.quartz.core.JobRunShell         ] - Calling execute on job MapDB_SchedulerGroup.Commit_Transaction
2017-06-29 15:45:15.651 [DEBUG] [rg.quartz.core.QuartzSchedulerThread] - batch acquisition of 1 triggers
2017-06-29 15:45:20.650 [DEBUG] [rg.quartz.core.QuartzSchedulerThread] - batch acquisition of 0 triggers
2017-06-29 15:45:20.651 [DEBUG] [org.quartz.core.JobRunShell         ] - Calling execute on job MapDB_SchedulerGroup.Commit_Transaction
2017-06-29 15:45:20.651 [DEBUG] [rg.quartz.core.QuartzSchedulerThread] - batch acquisition of 1 triggers
2017-06-29 15:45:25.650 [DEBUG] [rg.quartz.core.QuartzSchedulerThread] - batch acquisition of 0 triggers
2017-06-29 15:45:25.650 [DEBUG] [org.quartz.core.JobRunShell         ] - Calling execute on job MapDB_SchedulerGroup.Commit_Transaction
2017-06-29 15:45:27.817 [DEBUG] [.eclipse.jetty.server.HttpConnection] - org.eclipse.jetty.server.HttpConnection$SendCallback@56414b0e[PROCESSING][i=null,cb=Blocker@52f6ddec{null}] generate: FLUSH (null,[p=0,l=161,c=32768,r=161],false)@COMMITTED
2017-06-29 15:45:27.818 [DEBUG] [org.eclipse.jetty.io.ChannelEndPoint] - flushed 167 SelectChannelEndPoint@68b9e22f{/192.168.23.201:36998<->8080,Open,in,out,-,W,19774/30000,HttpConnection}{io=0,kio=0,kro=4}
2017-06-29 15:45:27.819 [DEBUG] [.eclipse.jetty.server.HttpConnection] - org.eclipse.jetty.server.HttpConnection$SendCallback@56414b0e[PROCESSING][i=null,cb=Blocker@52f6ddec{null}] generate: DONE (null,[p=161,l=161,c=32768,r=0],false)@COMMITTED
2017-06-29 15:45:27.820 [DEBUG] [.eclipse.jetty.server.HttpConnection] - org.eclipse.jetty.server.HttpConnection$SendCallback@e33e587[PROCESSING][i=null,cb=Blocker@3103adb4{null}] generate: FLUSH (null,[p=0,l=161,c=32768,r=161],false)@COMMITTED
2017-06-29 15:45:27.821 [DEBUG] [org.eclipse.jetty.io.SelectorManager] - Selector loop woken up from select, 1/1 selected
2017-06-29 15:45:27.822 [DEBUG] [lipse.jetty.io.SelectChannelEndPoint] - Key interests updated 1 -> 0 on SelectChannelEndPoint@2acc8e12{localhost/127.0.0.1:8080<->39909,Open,in,out,R,-,19759/0,HttpConnectionOverHTTP}{io=1,kio=0,kro=1}
2017-06-29 15:45:27.822 [DEBUG] [lipse.jetty.io.SelectChannelEndPoint] - Local interests updating 1 -> 0 for SelectChannelEndPoint@2acc8e12{localhost/127.0.0.1:8080<->39909,Open,in,out,R,-,19760/0,HttpConnectionOverHTTP}{io=0,kio=0,kro=1}
2017-06-29 15:45:27.823 [DEBUG] [org.eclipse.jetty.io.SelectorManager] - Queued change org.eclipse.jetty.io.SelectChannelEndPoint$1@6099ff74

Anyone an idea what this might be? Or ideas how to troubleshoot in more detail?
Instead of running all on DEBUG can I only run the PaperUI in DEBUG?
Thanks for your ideas.

Just found out this only happens when accessing PaperUI via myopenhab service.
When accessing naively I was able to create new binding configs.