Lost connection to server - Openhabian


during last Openhabian update I decided to update Node-Red also.
The Node-Red itself seems to be updated to v0.20.0 but it stopped working, as a result I get “Lost connection to server…” message from UI.
I’ve noticed that the installer couldn’t update Node.js and left old one.
Does anyone knows how to fix it?

Below update status:

Stop Node-RED                       ✔
  Remove old version of Node-RED      ✔
  Remove old version of Node.js       -
  Leave existing Node.js              -   Node v8.15.1   Npm 6.9.0
  Clean npm cache                     -
  Install Node-RED core               ✔   0.20.0
  Move global nodes to local          ✔
  Install extra Pi nodes              -
  Npm rebuild existing nodes          -
  Add shortcut commands               ✔
  Update systemd script               ✔

Also node-red-log after node-red-start:

12 Mar 22:34:47 - [info] Started flows
12 Mar 22:34:47 - [info] [mqtt-broker:ecc62bcb.53b478] Connected to broker: mqtt://localhost:1883
12 Mar 22:34:47 - [info] [mqtt-broker:349b5a3d.e108c6] Connected to broker: mqtt://localhost:1883
12 Mar 22:34:52 - [red] Uncaught Exception:
12 Mar 22:34:52 - TypeError: Converting circular structure to JSON
nodered.service: Main process exited, code=exited, status=1/FAILURE
nodered.service: Unit entered failed state.
nodered.service: Failed with result 'exit-code'.
nodered.service: Service hold-off time over, scheduling restart.
Stopped Node-RED graphical event wiring tool.
Started Node-RED graphical event wiring tool.
12 Mar 22:34:55 - [info]
Welcome to Node-RED
12 Mar 22:34:55 - [info] Node-RED version: v0.20.0
12 Mar 22:34:55 - [info] Node.js  version: v8.15.1
12 Mar 22:34:55 - [info] Linux 4.14.98-v7+ arm LE
12 Mar 22:34:56 - [info] Loading palette nodes


Node.js 8.15.1 is a valid supported LTS version so we don't force that to upgrade. If you really need to upgrade for some reason then you could use the nodejs.org install, but in general it should be fine on 8.15.

Thank you @dceejay
I finally managed to resolve it.
When I observed debug messages I've noticed that not all flows were dead, some of them were still working. The problem was only with Openhab specific nodes.
I copied the flows containing Openhab nodes and pasted them to fresh/new flows, after deployment all was back again.
Is this a bug that should by further analyzed by Openhab nodes developer?

probably... If you have a way to reproduce the issue I'm sure they would investigate.