This error can appear on your Ultimaker S5 when the printer failed to successfully download the firmware update files.
In most cases, this error can be resolved by performing the following steps:
- Restart the printer using the on/off switch, and perform the firmware update again. Instructions on how to update your firmware can be found in the Ultimaker S5 manual
- Ensure that your printer is connected to a stable network with an internet connection
- Perform a factory reset (Preferences > Maintenance > Factory reset). Please note that this deletes all Cura Connect related data, including analytics
If problems persist after taking these steps, please contact support by raising a support request above.