ER998 is a catch-all error, related to the software on the display of your Ultimaker S3 or S5. The exact origin of the error is unknown. However, other control systems of your printer are likely still working correctly. Ongoing processes, such as printing, are not interrupted by this error.
If your printer is on the Latest firmware channel and updated to version 6.5.0, your display will feature a refresh button. Refreshing the screen will only reboot the display software and can safely be selected, even during printing.
If your printer is on the Stable channel, this refresh button is not yet implemented. You can still control the printer remotely. The error message can be resolved by rebooting the machine. If the Ultimaker S3 or S5 is in the middle of a print job, or updating material profiles, please consider letting these processes finish before power cycling the machine.
Warning: Ultimaker Cura versions 4.9.1 and later feature the new Ultimaker PETG profile. This profile will automatically synchronize to your S-line printer if connected to the network, and it may be that the ER998 is displayed. If you see this error, please leave the printer for a few minutes to ensure any ongoing processes are finished. You may then reboot your printer. The error should not reoccur after this.
If you have recurring ER998 messages, you can help us troubleshoot by allowing sharing of anonymous data over the network. The error message logs will automatically be sent to us for analysis.
If the problem still persists, please contact support by submitting a support ticket.
Note: This error was formerly known as ER27.