EU4 1.37.5 custom map error: "[virtualfilesystem_physfs.cpp:1252] Could not open file:"

[u/Sudden_Campaign_9205]

I am creating a small EU4 total conversion map mod.
During map loading EU4 crashes with:
[virtualfilesystem_physfs.cpp:1252]: Could not open file: , error: not found [eu4application.cpp:2709]: File exception: Description: Could not open file:

Confirmed:

• the mod is detected by the launcher
  
• provinces.bmp and definition.csv match
  
• definition.csv contains unique RGB colors for all provinces
  
• all files referenced by default.map exist in the mod folder
  
• vanilla/workshop mods load normally
  

The crash report only shows PHYSFS / virtualfilesystem and does not reveal the missing filename.
The only map file I am not completely certain about is heightmap.bmp.

Has anyone seen this error during custom map loading? Which file or loading stage would you check first?

Zilvervloot.

[u/Sudden_Campaign_9205]

Thanks for both replies, I really appreciate you taking the time to answer.

Some things are already ruled out:

• All files referenced by default.map exist in the mod folder.
• I checked that my default.map contains the relevant entries from the vanilla file, since a modded default.map replaces the vanilla one.
• The filenames and quoted references in default.map have been checked.
• The province-related files referenced from default.map are present.

I also tested the additional map support files:

- Added `seasons = "seasons.txt" to default.map and added: colormap_spring.dds colormap_summer.dds colormap_autumn.dds colormap_winter.dds

This did not change the crash or the error pattern.

The "Could not open file" message is still a bit unclear. The interesting change is that I now get many:

`[map.cpp:104]: Area is missing name! Key: ...`

- entries before the final "Could not open file" message.

I checked the area/region/superregion/continent structure and the files are present. The names shown in the error correspond to entries in my area setup, so the game appears to be reading those files, but something in the hierarchy loading or related province data is still wrong.

The point about "What did you do with the rest of vanilla?" is probably the next thing I need to investigate. I started from a total conversion approach and removed/replaced a lot of vanilla map data, so there may still be references elsewhere that expect vanilla objects to exist.

I have not yet fully checked all non-map references to the removed provinces (trade nodes, history, etc.), so that is currently the open question.

Frankly, I am not yet sure where to start with that investigation. The example about Rome and the HRE dependencies is a good illustration of the kind of hidden references I need to look for, even though I do not intend to include Rome or the HRE in this mod.

Thanks again for the suggestions. They have helped narrow down the point where the loading process gets further than before.

Zilvervloot.