he added these 5 lines as stated in post #1
hdmi_force_hotplug=1
hdmi_force_edid_audio = 1
hdmi_group=2
hdmi_mode=39
enable_uart=0
tho later stated these two lines may all that be needed
hdmi_force_hotplug=1
hdmi_force_edid_audio = 1
But you just said that taking those out again does not cause the problem.
No...
Those two lines are the ones that are needed.
Without them the LEDs don't work.
If the lines are in the config.txt file, the LEDs work.
We are going round in circles. What did you do that removed the missing libraries issue, which you can then revert and make the missing libraries issue return?
Note: I have RPiOS Bullseye not Buster.
The problem might be that the npm post install script checklib.js checks for the existence of /usr/local/lib/python2.7/dist-packages/unicornhat.py.
Since Debian has finally got rid of Python2, this file is not installed by the Pimoroni script and so the warning remains if you try again to install the node.
The changes to /boot/config.txt make no difference to the installation warning.
I don't have a neopixel strip so I don't know if it works regardless of the python2 library.
Can @dceejay or @knolleary (you are listed as the maintainers 
) take a look at that checklib.js and see if it's correct in these python3 days?
Edit - the Pimoroni script installs /usr/local/lib/python3.9/dist-packages/unicornhat.py, on my Pi at least.
indeed that is unlikely to work... and so will create that warning... Sure we can patch that
According to the pimoroni/unicorn-hat GitHub page you āmightā need to add
hdmi_force_hotplug=1
to get the LEDs to light depending on what else you have installed on the Pi.
So that is not a NR requirement/issue, it is an issue with the code that runs the hat possibly having problems because of something else you have installed or some setting you have activated in the Piās configuration.
The Pimoroni install script for the device does set that (or it did when I just tried it) as long as you say yes when it asks to modify your setup
OK - I just tweaked the checklib test to include 3.9 so it shouldn't warn on default python 3 install an more.
To test I flashed SD card with minimal bullseye.... booted configured network etc and applied latest updates. Ran the prereq Pimoroni neopixel install script as per readme, saying yes to allow modification to audio setup and no to all examples. Rebooted as requested... Ran Node-RED install script - added node-red-node-neopixel node - checked no errors - loaded up Node-RED - added neopixel node with simple test - All good... no extra tweaking of boot files necessary.
the end.
3 Likes
Thanks and very much appreciated.
To recap the WHOLE story from DAY ONE - just so things are clear for anyone who may be reading this and not sure what is going on.
=-=-=-=-=-=
I had Jessie (or Stretch - which ever is just before Buster) running on a RasPi 3B+ and the LED strip was working.
One day during an update power was lost and the SD card wouldn't boot. It was NOT corrupted as in kaput. Just the update was interrupted at a critical time. (Moving on)
I wanted to get that machine back up and working.
NEW (out of the box) SD card. Installed BUSTER, and the other stuff. (Not NR at this point)
Got it working/booting.
Installed NR to a very recent version.
Did that curl command to get/install the pimoroni stuff - remembering a long time ago when I made the same mistake and was prompted to check I had installed ALL the requirements. (That stuck with me) 
Copied the flow stuff from the old card.
cd .node-red
npm -install
Got all the nodes installed as required.
Started Node-Red.
Flows running.
NO LED functionality.
$hit!
Walked away.
Months later came back. Tried again. Same: not working.
Dug a hole looking at why. "Get them working from the RasPi point of view".
Went down that path. Again: nothing useful. Just pointed to the stuff I had already done.
Recently Started digging again.
Decided to install the neo-pixel node from the CLI.
missing libraries
Ah! Bingo! That'll be the problem.
Another 2 weeks messing around trying to find them.
No luck.
Ran the pimoroni script a few dozen more times (confused by the "This command uses sudo" in the instructions)
Anyway: Nothing improved.
During the installation the script was saying that it will force audio out the HDMI port and that patches will be done.
Then the machine needs to reboot.
Yeah, ok.
Did that many times as well.
There were mentionings of the two lines here and there. But TOGETHER and only implicitly said.
Not: You must have these lines in the config.txt file, or it won't work.
Somewhere around this time I dug up two SD cards from other machines.
One was Jessie, one was Stretch. They both have NR installed. Old-ish version but new enough to test.
(Both were in a RasPi ZW and had the ribbon camera plugged into them)
Left them as they were software wise, but plugged them into the other machine with the NeoPixels.
Ran the pimoroni script.
Rebooted.
Installed the neo-pixel node. (With errors)
Wrote a basic flow to turn on all the LEDs.
NOTHING.
Both SD cards.
This compounded the frustration as there should be no reason anything ELSE would be wrong.
Got ANOTHER sd card with BUSTER from a RasPi 3B+ that has no external hardware.
Put it in.
Same. (LEDs not working)
25 Feb 2022
About 4 days ago, out of there's nothing else left to do, I was looking at the old SD card's config.txt file and noticed these five lines. Yeah, I got it down to two, but this is the FULL story.
Put them in, rebooted.
The LEDs work.
Out of interest I tried installing the neo-pixel node again - why not?
Again got the error about the missing libraries.
Weird. Not blaming anyone. But what the....?
@dceejay Thanks. I appreciate what you did. Others may waste a lot of time if they install the node from the CLI and see that error - as I did.
Not wanting to flog a dead horse:
It seems that you need these 4 lines:
hdmi_force_hotplug=1
hdmi_force_edid_audio = 1
hdmi_group=2
hdmi_mode=39
I was recently (as in very) messing around and the LEDs stopped working again.
This is/was because I use VNC and had changed the resolution of the screen to better fit the monitor.
When I looked at the /boot/config.txt the hdmi_mode and hdmi_group were set to something else.
Putting them to what is shown, the LED's started to work again.
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