Node RED UI will not show up

Third party integrations Node-RED
1

Hi Community,

I guess I need your support: How to start Node-RED-UI without flows running from the beginning?

I changed an existing flow and after a restart of Node-RED the Node-RED-UI won’t show up anymore. Using Home Assistant’s side bar Node-RED shows a blank page. Using IP-address (192.168.x.x:1880) the browser shows “busy” and some minutes later also a blank page. All other functions of Home Assistant are up and running.

Restart of Node-RED or of the whole system won’t change the behavoir. The protocoll in Supervisor → Node-RED doesn’t show any untipical entries. HA-Supervisor shows that Node-RED causes 28% of the CPU load (RPi4)!

That leads me to the assumption that I may generated an infinit loop with the last edit of the flows (looped back a signal to input). I guess Node-RED could be too busy to start the UI. While Node-RED-UI won’t show up I can’t change the flow to solve the issue.

Any ideas?

Best regards - Marco

2

You can just delete or edit the flows.json in your nodered folder.

3

Okay. You mean with a text editor like notepad++? But it is quite hard to read for an unskilled like me. Or I have to cut out a big pice of code like a whole TAB.

Any other hints?
Thanks!!

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4

Just remove it to start from a clean slate. Then import it back in, and undo your last changes.

5

ROOT CAUSE
By mistake I created an infinite loop inside a Node-RED flow (connected output from nodeA to input of nodeB and output of nodeB to input of nodeA). After deploying the change this infinite loop caused a high CPU load on my RPi4. After a restart of the Node-RED add-on the user interface in Home Assistant never came up again. The add-on showed 25% CPU load instead of the normal approx. 1%.

SOLUTION

I disabled the tab with the infinite-loop-flow manually and restarted the Node-RED add-on. The userinterface showed up again. Afterwards I could repair the flow and activate the tab again. - DONE :+1:

I used SAMBA to access the right folder (\\config\node-red\flows.json and opend the flows.json with an text editor (e.g. notepad++). At the very beginning I found
...,"type":"tab","label":"<YOUR TAB NAME>","disabled":false,...
I replaced the false with true to disable the tab, saved the file and restarted the Node-RED add-on.

The deactivated tab means that the flow will not be processed.

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