I restored an OctoPrint backup to a new install, but the LEDs no longer work?
It is likely that the OS level config is incorrect. To fix this, please head to the OS Configuration Test section (under 'Utilities') to run a test and fix the configuration. See the OS Configuration Test docs.
Unable to initialize SPI
If you get the error:
ws2811_init failed with code -13 (Unable to initialize SPI)
From the plugin_ws281x_led_status_debug.log then it likely means that you have some extra peripherals attached to your Pi, that are taking up the SPI channels, therefore conflicting with the plugin's use of SPI.
A user reported that SPI failed to initialise with the above screen, however commenting out the lines the guide asked you to enter meant that both the screen and LEDs could work at the same time.
No LED output on a Raspberry Pi 4B (rev 1.4), and the log says 'Unsupported board'
The dependency that this plugin relies on was not updated to add support for these boards as of the last release of the plugin. Please see this issue for instructions of how to fix it.
Little/no LED output when not using a level shifter
Some strips do not like 3.3V signals, and if you do use 3.3v (without a level shifter) then please keep the wires to the LEDs fairly short to avoid voltage drop.
Mixed reports that using a sacrificial LED on a short wire (to avoid voltage drop) can be beneficial for the LED strip. See this Hackaday article for more details. This solution is untested, only linked because it might be useful.