When publishing a feature service using a map with unique value symbology based on a subtype field, the symbology class values must exist in the subtype. The error includes the Value and Label values for the symbol class that does not have a corresponding subtype. The dataset name and subtype field are also provided.
Compare the Value and Label values from the Symbology pane with the Code and Description values for subtypes of the dataset. Remove any symbol classes from the Symbology pane that do not reference a subtype value. The Subtypes view can be used to manage subtypes for the dataset.
Alternatively symbolize using a different field.
For more information, see Symbolize feature layers and Modify unique value symbology.