E12 indicates overflow detection in Midea L11. If the water level is rising or there is water outside, stop the supply and avoid triggering another alarm with a new cycle.
The L11 technical manual checks for an excessive water level condition. The code alone does not let you determine whether the fault is the valve, the level reading, or the electronics.
Document it without repeating the fill
Watch to see whether water kept entering after you stopped the program and whether it spilled out of the appliance. Close the shutoff valve if you can access it safely. Do not open it again just to prove the problem happens repeatedly.
If water reaches electrical connections, avoid contact and get help to isolate power from a dry, safe location. Do not force the door or tip the machine to remove water from its base.
Even if the visible water level has dropped, keep the E12 code and request a check if it comes back. Do not enter the service mode in the technical document or blow into pressure tubes: interfering with the detection can affect fill protections.
Service should check the source of the overflow and its detection; clearing the alert does not prove the circuit is working properly.