[2022] How to force spawning of freight trucks?

How is your storage buildings doing? Are all their trucks in use?

The error basically tells you that the internal storage of those buildings is empty and they haven't received a delivery in time. To fix that you will want to have enough storage buildings so that they have free trucks, that can respond to requests for goods.

This guide goes into a bunch more detail on how to use storages and the typical problems when they aren't working as they should.

https://steamcommunity.com/sharedfiles/filedetails/?id=1550292479