Node-Red will not connect to URL on Raspberry Pi

#1

After configuring a flow and deploying it, I cannot access the URL provided in the Node-RED console terminal anymore. I am attempting to display thermocouple temperatures with an Adafruit MAX31855 K-type thermocouple breakout board. One of the error messages that shows up is that there is no module named Adafruit_GPIO.SPI. When opening up Node-RED on the Raspberry Pi, the error messages loop. Here is what I see when opening Node-Red:


Start Node-RED
 
Once Node-RED has started, point a browser at ____________
On Pi Node-RED works better with the Firefox or Chrome browser
 
Use   node-red-stop                          to stop Node-RED
Use   node-red-start                         to start Node-RED again
Use   node-red-log                           to view the recent log output
Use   sudo systemctl enable nodered.service  to autostart Node-RED at every boot
Use   sudo systemctl disable nodered.service to disable autostart on boot
 
Starting as a systemd service.
Started Node-RED graphical event wiring tool.
29 Mar 15:05:25 - [info]
Welcome to Node-RED
===================
29 Mar 15:05:25 - [info] Node-RED version: v0.20.3
29 Mar 15:05:25 - [info] Node.js  version: v10.15.3
29 Mar 15:05:25 - [info] Linux 4.14.79-v7+ arm LE
29 Mar 15:05:26 - [info] Loading palette nodes
29 Mar 15:05:30 - [info] Dashboard version 2.14.0 started at /ui
29 Mar 15:05:30 - [info] Settings file  : /home/pi/.node-red/settings.js
29 Mar 15:05:30 - [info] Context store  : 'default' [module=memory]
29 Mar 15:05:30 - [info] User directory : /home/pi/.node-red
29 Mar 15:05:30 - [warn] Projects disabled : editorTheme.projects.enabled=false
29 Mar 15:05:30 - [info] Flows file     : /home/pi/.node-red/flows_raspberrypi.json
29 Mar 15:05:30 - [warn]
---------------------------------------------------------------------
Your flow credentials file is encrypted using a system-generated key.
If the system-generated key is lost for any reason, your credentials
file will not be recoverable, you will have to delete it and re-enter
your credentials.
You should set your own key using the 'credentialSecret' option in
your settings file. Node-RED will then re-encrypt your credentials
file using your chosen key the next time you deploy a change.
---------------------------------------------------------------------
29 Mar 15:05:30 - [info] Starting flows
Adafruit MAX 31855: Checking for muxing... 0
29 Mar 15:05:30 - [info] Started flows
29 Mar 15:05:30 - [info] Server now running at ____________________
29 Mar 15:05:30 - [red] Uncaught Exception:
29 Mar 15:05:30 - Error: ImportError: No module named Adafruit_GPIO.SPI
    at PythonShell.parseError (/home/pi/.node-red/node_modules/python-shell/index.js:183:17)
    at terminateIfNeeded (/home/pi/.node-red/node_modules/python-shell/index.js:98:28)
    at ChildProcess.<anonymous> (/home/pi/.node-red/node_modules/python-shell/index.js:88:9)
    at ChildProcess.emit (events.js:189:13)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:248:12)
    ----- Python Traceback -----
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.
29 Mar 15:05:33 - [info]
---------------------------------------------------------------------------------

This message continuously repeats in an ongoing loop. When attempting to follow the URLs presented in the above message from Node-RED, the following message is given in the brower: 

This site can’t be reached
10.0.0.41 refused to connect.
Try:

Checking the connection
Checking the proxy and the firewall
ERR_CONNECTION_REFUSED

So far, I think that it could be an issue with the MAX31855 module, the connection to the server, or the error message that is about flow credentials.

Thank you for your help.

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#2

Hi,

the error is with whatever node you've installed to try to access the device. Which node are you using?

It is a fatal uncaught error that is crashing Node-RED. Nodes should not do that - so you should raise an issue against the node.

As you are on version 0.20.3, you can take advantage of the new safe mode to start node-red without your flows running.

Open a new terminal and run node-red-stop. Then run node-red --safe - that will start Node-RED in safe mode. You should then be able to access it in your browser, edit/remove the offending node and deploy - at which point it'll exit safe mode and start your flows. If it still crashes, restart in safe mode and try again.

Once you've got it stable, stop node-red (ctrl-c in the window you can node-red --safe in), then restart it as a service with node-red-start.

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#3

Thank you so much for your reply, deleting the faulty node worked. The node is called "adafruit max31855". One thing that I believe could be an issue is that I may need to use the default SPI pins rather than bit-banging GPIO pins. Whenever I enter bit-bang GPIO pins into the node, they are erased the next time I open the node.

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#4

The Node doesn't seem to check that the required adafruit python libraries are installed (and that spi is enabled). Their readme should at least mention those pre-reqs. Please raise an issue against that node to at least improve the docs.

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