This is an error that is not recognized by your Ultimaker S5 / Ultimaker S3. It can occur when there is a mismatch between the installed electronics and firmware.
This can usually be resolved easily by following these steps:
- Power cycle the printer using the on/off switch. Wait until the printer has completely shut down before turning it on again
- Update the firmware to the latest stable version
If the problem still persists, please contact support by raising a support request above.