Getting the "Not Enough Goods to Sell" error message while playing Cities: Skylines can be very annoying. It is an indication that your industry and by extension, your city expansion, is being seriously undermined in productivity. So how do you fix it?
Increase Your Industry
Commercial districts needs goods to sell to your citizens. If you do not have an industrial zone, or your industrial zone is very small, then you will likely be mostly importing your goods. Importing goods can raise costs for goods, making commercial areas purchase smaller quantities. The import trucks and other vehicles also may not deliver quickly and plentifully enough to satisfy residents.
To remedy this, make sure to make room on your map for a sizeable industrial zone. When you do increase or create your industry area, make sure to be wary of pollution, as this zone produces a lot. You will also want to make sure to have enough low education residents to work the jobs.
If you decide you want to keep importing at some level, then you need to take a look at your transportation. The biggest area to pay attention to is highways. Trucks will carry cargo across your highways to deliver. Make sure all areas of your highway are free of traffic or other deterrents. Trucks will not always use your main entrance, so check everywhere on the map.
You should do the same checking for boats, trains, and any other cargo pulling transportation. Once everything runs more smoothly, you should see the not enough goods error resolve itself.
Want to read more about Cities: Skylines? Check out How to Get More Workers in Cities: Skylines on Pro Game Guides.