This article includes the following information about SmoothieErrors:

  1. Background

  2. Common preliminary questions: Context of error

  3. Types of error messages


A SmoothieError is how the OT-2 reports something that went wrong with a motor controller command. It is usually a symptom of an underlying mechanical or electrical problem. A variety of things can cause a SmoothieError.

SmoothieErrors indicate problems with the motor controller board and have a specific code (G-code) that dictates how you should read them. A working knowledge of G-code often gives you more information for troubleshooting. For example, it can help you narrow down the cause of potential SmoothieErrors.

Common preliminary questions: Context of error

Listed below are questions you can use to start diagnosing and troubleshooting a SmoothieError. Opentrons Support may also ask you to provide some or all of this information if you encounter a SmoothieError.

1. What were you and the robot doing when this error popped up?

  • Take note of as many details as possible that span the set-up of the OT-2 for your protocol(s) up until the point the error occurred:

    • At what step did this problem arise during your use of the OT-2?

    • Was there a physical crash or any contact the pipette had with labware/OT-2 recently? Did this bring up the error?

    • Does this routinely happen in your protocol/calibration steps?

    • Has this happened before with this specific pipette in use?

2. Was there anything that you were doing prior to this issue occurring that might have caused it?

  • Examples of this might be:

    • Using non-Opentrons tips

    • Updating from a much older software version

    • Having previous issues with your OT-2

3. Take a photo of the robot when it caused this error as well as the error message or the exact text that pops up.

  • A video recording can also be extremely helpful, but be sure to check that recreating the error state won’t physically damage the pipette/OT-2 component.

4. How many pipettes are connected to the robot?

5. Were you able to successfully connect and use these pipettes in the past?

6. Can you download the logs from the OT-2 and send them over to the Support team for further investigation?

Types of error messages

There are two common SmoothieErrors: Homing fail and hard limit. See below for examples.

  • Example homing fail error message:

M907 A0.1 B0.05 C1.0 X0.3 Y0.3 Z0.1 G4P0.005 G28.2C returned ALARM: Homing fail
  • Example hard limit error message:

M907 A0.1 B0.5 C0.05 X0.3 Y0.3 Z0.1 G4P0.005 G0B3.5 returned ALARM: Hard limit -B

A SmoothieError can look like one of the two error messages shown below.

1. Example SmoothieError message that occurs during protocol runs, calibrations, and homing:

2. Example SmoothieError message that occurs specifically during Robot Calibration Check:

If you receive a version of the first error message, proceed to the appropriate subpage to continue troubleshooting:

If you see the “Robot Calibration Check” error message, please review the logs you downloaded to identify the type of SmoothieError you are experiencing before proceeding to the appropriate subpage.

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