Not queuing T0, that tool doesn't exist according to the printer profile or was reported as invalid by the firmware. Make sure your printer profile is set up correctly.
What did you already try to solve it?
Nothing yet
Have you tried running in safe mode?
Yes
Did running in safe mode solve the problem?
No
Complete Logs
octoprint.log, serial.log or output on terminal tab at a minimum, browser error console if UI issue ... no logs, no support! Not log excerpts, complete logs.)
WRITE HERE
Additional information about your setup
OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible
running into the same issue. Geeetech A20M Sliced with Prusa 4.8.0 and trying to print in 2 colors.
Terminal (supressed temp messages):
Changing monitoring state from "Operational" to "Starting"
Send: N0 M110 N0125
Recv: ok
Changing monitoring state from "Starting" to "Printing"
Warn: Not queuing T0, that tool doesn't exist according to the printer profile or was reported as invalid by the firmware. Make sure your printer profile is set up correctly.
Send: N1 M8224
Recv: ok
Send: N2 G28*17
I setup dual extruder with shared noozle.
When printing from SF-Card instead of octoprint, everything is fine.
I will try to upload more logs, unfortunately I first deleted them to get fresh one, now have
to look to create new
There is a printer profile in Cura, a printer profile in OctoPrint, and the firmware configuration. All three need to agree.
I believe we are going to need a serial.log (it needs to be enabled first, click for more info).
Using a simple two color object (like a 4x4x4mm cube with the top half one color and the bottom half the other color), please post the gcode your slicer generated and the serial.log of the attempt to print that object.
The terminal output you posted doesn't make any sense because you didn't use the </> button to surround it and the markdown code this forum uses ate some of the characters. There is also no command with T0 as a parameter so its hard to tell exactly what happened.
I'd like you to try in safe mode (another link for more info). You have plugins installed and lots of errors in your octoprint.log which makes it hard to tell exactly what is going on.
The firmware for the A20M is pretty clever and the slicer is pretty dumb.
M104 S200 T1 is rejected by the printer firmware because it knows that there's only one nozzle. This rejection is ignored when printing from the SD card but shows up as a non-fatal error when printing via OctoPrint.
The error appears to be non-fatal so you can just ignore it. You could post a bug report in Ultimaker's Cura forums and hope they can "fix" it in a future release.