This is a new (weird) error

While optimising some flows, etc, I got this error:

FileError: '' wasn't found (0)

in app.min.less 

Google isn't that helpful.


Try restarting node red and force a full refresh of the browser. If it still happens then more information is required I think.


But in the mean time, it has gone away.

I probably rebooted the machine and all started working again.

The post is old......

I have the same problem on a Tablet with android, just after to run node-red update.

Any comment or help?

Have you tried resetting the browser cache?

Yes but there were no changes

also try other browsers (opera mini, Chrome, etc) and shows the same error :frowning:

Then please try restarting Node-RED and posting the startup log here

This is the log

My node-red run on raspberrypi B 3

pi@raspberrypi:~ $ node-red-start

Start Node-RED

Once Node-RED has started, point a browser at xxxxxxxxxxx:1880
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

To find more nodes and example flows - go to

Starting as a systemd service.
Started Node-RED graphical event wiring tool.
30 May 14:26:04 - [info]
Welcome to Node-RED

30 May 14:26:04 - [info] Node-RED version: v0.20.5
30 May 14:26:04 - [info] Node.js version: v8.11.1
30 May 14:26:04 - [info] Linux 4.19.42-v7+ arm LE
30 May 14:26:07 - [info] Palette editor disabled : npm version too old. Requires npm >= 3.x
30 May 14:26:07 - [info] Loading palette nodes
Thu, 30 May 2019 17:26:12 GMT node-telegram-bot-api deprecated Automatic enabling of cancellation of promises is deprecated.
In the future, you will have to enable it yourself.
See at module.js:652:30
30 May 14:26:18 - [info] Dashboard version 2.14.0 started at /ui
30 May 14:26:19 - [info] Settings file : /home/pi/.node-red/settings.js
30 May 14:26:19 - [info] Context store : 'default' [module=memory]
30 May 14:26:19 - [info] User directory : /home/pi/.node-red
30 May 14:26:19 - [warn] Projects disabled : set editorTheme.projects.enabled=true to enable
30 May 14:26:19 - [info] Flows file : /home/pi/.node-red/flows_raspberrypi.json
30 May 14:26:19 - [info] Server now running at
30 May 14:26:19 - [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.

30 May 14:26:19 - [info] Starting flows
AC: :
AC: :
AC: :
30 May 14:26:30 - [info] Started flows
30 May 14:26:31 - [error] serial port /dev/rfcomm2 error: Error: Error: No such file or directory, cannot open /dev/rfcomm2
30 May 14:26:31 - [info] serial port /dev/ttyACM0 opened at 9600 baud 8N1
30 May 14:26:31 - [info] serial port /dev/ttyUSB0 opened at 9600 baud 8N1
30 May 14:26:31 - [error] [function:Output Filter: Temperatura] SyntaxError: Unexpected token u in JSON at position 1
30 May 14:26:31 - [error] [function:Output Filter: Humedad] SyntaxError: Unexpected token u in JSON at position 1
30 May 14:26:31 - [info] [mqtt-broker:61e2e87f.71cd08] Connected to broker: mqtt://localhost:1883

So how did you update node-RED?
As this is on a raspberry pi did you use the upgrade script as suggested in the raspberry pi age in the docs?
If not try running the script which should fix some of the issues in the logs.