Display stuck after a Moonraker update (fixed)

This is fixed. A machine still showing it has not been updated yet.

There is one thing to do, and it has two halves

Update every component, then flash the Octopus. Both halves, in that order. Nothing else is needed and nothing else should be attempted.

Symptoms

• The display shows Error getting Moonraker server info: Unauthorized
• It retries forever and never reaches the interface
• Mainsail in a browser works normally, which is what makes this confusing — the printer itself is healthy
• Printing from the web interface still works; only the screen is unusable

The fix

1. Update every component. In the Update Manager, press UPDATE ALL COMPONENTS — see Updating the printer

2. Let it finish and restart. The printer performs a firmware restart on its own; reboot it from the dashboard afterwards

3. Flash the Octopus. The host has moved and the main board has not, so it now reports itself out of date. Put the current firmware.bin on a microSD card and let the board take it — the full procedure is Flashing the control boards

4. Check the screen. It should reach the interface within a few seconds of the restart

The Octopus flash is part of the update, not an optional extra

Updating the software without flashing the board leaves the two out of step. Do both. A machine that has taken the update is not finished until the Octopus is running the current firmware.

Not while a print is running

Updating restarts Moonraker and Klipper, which drops the connection between the printer and every interface. Finish or cancel the job first.

What was actually wrong

KlipperScreen’s shipped example configuration carried the line moonraker_api_key = False. KlipperScreen read that as a key and sent the literal string False — a value that looks like a credential and is not one.

Moonraker used to ignore it and fall through to trusting anything connecting from the machine itself. Moonraker 0.11 stopped ignoring it: a change on 2026-08-17 made credential checking strict, so an invalid key is refused outright instead of being passed over.

Reproduced on a G1 on 2026-08-30, the two logs side by side read:

KlipperScreen:  {'code': -32602, 'message': 'Unauthorized'}
Moonraker:      101 GET /websocket?token= (127.0.0.1) [_TRUSTED_USER_]
                JSON-RPC Request Error - printer.objects.subscribe, Unauthorized
                JSON-RPC Request Error - server.files.list, Unauthorized

The connection is accepted as a trusted local client, and then every request through it is refused. The bogus key is validated, fails, and the failure revokes the trust the connection already had.

Neither side was broken as such — KlipperScreen relied on Moonraker being lenient, and it stopped being. It was fixed upstream on 4 September 2026, and Ginger’s KlipperScreen was brought onto that code on 9 September. Neither builds that token parameter any more.

Related notes

• Updating the printer — the update itself
• Flashing the control boards — the second half
• Mainsail dashboard basics
• G1OS software stack — why KlipperScreen and Moonraker are separate services
• Display screen