Ender 3 v2 - M600 Change Filament Issues

Using Octoprint 1.6.1 and today’s Merlin build via the subscription (here) leaves octoprint stuck in a “Pausing” state.

The issue appears to be similar to this Change filament (M600) disconnects octoprint from printer · Issue #21143 · MarlinFirmware/Marlin · GitHub

If you have done a fresh installation, make sure to perform a factory reset of your printer.

Via Octoprint, this can be done with:


Set your printer up again, and you should be good to go.

There’s a long, boring explanation about stored EEPROM settings and firmware upgrades happening, but the above should get you going again.

Thank you for the quick response, I will try this today.

OK, I tried M502 via the octoprint terminal but started seeing comms issues and it wouldn’t accept M500. I did factory reset and store settings via the ender 3 LCD. What do I do now?

WARNThe received line contains at least one null byte character at position 0, this hints at some data corruption going on

Turns out factory reset must also change the baud rate so the serial comms went down.

The serial port should be 115200 - however if you have the meatpack plugin, Octoprint might have been talking binary to the printer and wouldn’t have gone out of Meatpack mode until the printer was powercycled.

Are you back able to talk to the printer again correctly via Octoprint?

Yes, thank you, explicitly setting the baud rate fixed the problem.

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