20004: Layer uses a simple line symbol with a style other than solid

Your layer contains a simple line symbol with a line style other than solid. The display of this symbol in a basemap layer or optimized map service will potentially differ from your standard ArcMap display.

Solutions

• Do nothing. Simply accept the new symbol drawing as is.
• Alternatively, you can change the line symbol to a cartographic line symbol with a similar dash pattern.

More information

This warning message is simply telling you the simple line symbol may appear different in a basemap layer or an optimized map service. This is because this type of symbol will draw as a solid style at a size larger than 1 point in ArcMap's display. In general, cartographic line symbols offer more control and better appearance than simple line symbols when drawing with patterns.