A layer in your map is rendered using an unsupported dot density option.
- Uncheck the Maintain Density option or specify that the density be maintained by Dot Value.
- Alternatively, remove the map layer that uses Maintain Density with the Dot Size option.
When using the dot density renderer to symbolize a layer in a basemap layer or a map service, the level of gray is maintained by changing the number of dots and their dot value as you change the scale of your display.
If the Dot Size option is used to maintain density, the size of the symbol would be used to maintain the grayness of the display.
See Using dot density layers for more information.