Hi Terragon and welcome to Vox.
You're right with your assumption. This error is caused by deleting (and creating new) countries, because the ID chain can get interrupted. I don't know under what circumstances it exactly happens, but it's more likely the more you delete (and re-create). The programmer (dustin) would have to further comment. It's actually an old error.
If you open a map file (.voxb, plain XML) with a text editor, you can see a country defined as follows (example):
Code: Select all
<voxPoints>940,173 948,197 901,205</voxPoints>
<polygon>877,592 878,591 906,585 940,592 990,595 1005,601 1003,637 994,650 981,662 972,663 959,656 946,658 936,664 927,660 903,637 894,626 878,599</polygon>
Important here related to this problem are the parts <id> (country ID itself) and <adjoining> (IDs of connected countries). All countries have to be set up in an uninterrupted chain which is normally done by the map editor and saved to the .voxb file. For instance, 31 countries need to have IDs 0..30.
If you get this error, it can only be fixed by manually editing the .voxb file and correcting the ID chain, a likely annoying task.
Sadly, there's no handy fix to correct it, but if you know how it's caused (and you do now), you may avoid it and even correct it yourself, should there be no other way left.
Looking forward to see a map of yours uploaded for review to be later available for online play.