ER20 - Safety circuit error

If you receive this error message, it means that the safety circuit of the mainboard has been activated.

Older versions of the Ultimaker 3 mainboard have two safety jumpers installed. If one of these is missing, this will trigger the ER20 message. To check if this is the case, you will need to access the electronics at the bottom of the printer.

UM3-Turn-printer.jpg UM3-Mainboard-cover.jpg UM3-Safety-jumpers.jpg
1. Place printer on its side 2. Remove cover 3. Check jumpers

Gently place the printer on its side, then manually lift up the Z stage.


From the inside of the printer, remove the two bolts that secure the cover and place the cover aside.


If your printer has an older version of the mainboard, the two safety jumpers should be installed in the corner.


On newer versions of the mainboard, many unused connectors were removed. This includes the connectors for the jumpers. You can easily tell them apart:

UM3-Mainboard-1548.jpg UM3-Mainboard-2296.jpg
Old mainboard (1548) New mainboard (2296)

Note: If problems persist after taking the steps on this page, contact support or your local reseller. Ensure to include the error number and the log files of your printer.

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