The printer displaying the message: Another action is already running. Finish this action directly using the printer's touchscreen.
Error name: Another action is already running.
Error code: #10506
This error is displayed in case of action being illegal with respect to the printer's state. For instance, this can be a result of manually sending 'move axis' commands during print. The UI should not allow starting such an action. In case this happens it is due to a bug or poor synchronization of a remote user interface.
Make sure your printer's firmware is updated, and that the network the printer is connected to is stable.