This is a kind of fault, which a device can detect and cure by itself. However, in some cases it does not. If you have run into such a situation, run a 90°C cotton cycle or Eco Drum Clean (not all models have it). Do not use detergents or load anything in the drum. If the error is still there, check and clean filters and hoses. Eliminate clogs, if any. Run a spin cycle and drain all remaining water.