I'm running into an issue that I can't seem to find a fix for, and it's preventing me from doing anything with s&box.

If I import or create a map in Hammer, hit F9 or select "File > Build" from the menu, and build the map, the build seems to run fine but the S&box editor opens and plays the "minimal" default scene with an error message:

`engine/ResourceSystem Error loading resource file "maps/test1/world_physics.vphys_c" (Error: ERROR_FILEOPEN: File not found)`

I'm new to s&box (coming from Unity). I've tried troubleshooting everything I can find through web searches and AI suggestions:
  • Verified integrity of s&box files through Steam
  • Started fresh project with basic/blank templates in C:\sbox_temp to avoid naming conflicts, named the project "test1," named my map "map1"
  • In Hammer, put a single cube with the brush tool in the map at 0, 0, 0, aligned with the grid, and added an `info_player_start()` spawn object at 0, 0, 25, with nothing else in the map. Default texture, verified Physics Type was set to "default
  • Made sure .NET SDK was at v10
  • Uninstalled and reinstalled s&box through Steam
  • Closed everything, cleared .source2 contents, re-opened, and ran Build again
  • Run sbox-dev as Administrator
  • Looked through generated logs in sbox/.source2/sentry and didn't find anything referencing silent failures during Step 2: phys stage, or any logging related to missing files, crashes, etc.
  • Updated NVIDIA GPU driver
I saw that this happened after an update a few years ago, but the issue seems to have been resolved. I haven't found much information about this being an issue since then.

S&box version: 26.10.13c through Steam
Hammer version: April 2026 (most recent)
OS: Win11 (most recent update)
CPU: 12th Gen Intel(R) Core(TM) i7-12700H
GPU: NVIDIA GeForce RTX 3070 Laptop GPU

Any suggestions or help is greatly appreciated!