Firmware confusion, please help.
Hi. I bought my MK2 a few years ago, just before the MK3 came out. For the last 2 years I have been moving, building a house and the printer has been packed away until this month. I never upgraded firmware or the slicer until now. I just downloaded and installed the latest slicer and firmware (v 3.2.3) Now, I get the "upgrade to 3.9" bug anytime I start a print.
Additionally, I'm not real happy with the new firmware. Twice now a print has halted for some reason with an error message like "Load new filament" or something like that, I don't recall exactly. Anyway, the hotend stays hot during this entire time! I had one quit in the middle of the night and was probably in this error state for 4 hours.
Check whether you have installed the correct firmware for your printer.
Check whether you have selected the correct printer in the slicer - if you slice for a MK3s, it should already tell you that you sliced for a different model when inserting the SD card, but it may result in the recommendation to update your (non-existing) MK3s to that model´s newest firmware.
Halting with an error for unloading/loading filament sounds like a badly adjusted filament sensor, not like a firmware bug.