The error:
When building a RealityKitContent package that contains a USDZ file exported from Blender, Xcode throws the following error:
error: [xrsimulator] Exception thrown during compile: Cannot get rkassets content for path .../RealityKitContent.rkassets because 'The file "RealityKitContent.rkassets" couldn't be opened because you don't have permission to view it.'
error: Tool exited with code 1
The error message mentions "permission" — but permissions are not the issue. This appears to be a misleading error from realitytool masking a USD validation failure.
What I've ruled out
File permissions — all files are -rw-r--r--, user has Read & Write on the folder
Extended attributes / quarantine flag — other files with the same @ flag work fine
Corrupted archive — unzip -t confirms the USDZ is valid (board.usdc + textures)
Stale build cache — deleted DerivedData and com.apple.DeveloperTools cache, no change
Key observations
The same file builds successfully on my colleague's machine running identical Xcode 26.3 - MacOS 26.3
Other USDZ files in the same .rkassets bundle (downloaded from Sketchfab, or created in Reality Composer Pro) compile without any issue.
Only USDZ files exported directly from Blender are affected.
When the file is placed in Bundle.main and loaded via Entity(named:in:.main), it works perfectly — no errors
Reality Converter flags the file with two errors: UsdGeomPointInstancers not allowed, and root layer must be .usdc with no external dependencies
The confusing part: the same file compiles fine on an identical Xcode 26.3 setup and importing method. This suggests either a machine-specific difference in Xcode's validation behavior, or a cached .reality bundle on my colleague's machine that isn't being recompiled.
Current workaround:
Loading from Bundle.main instead of the RealityKitContent package bypasses realitytool entirely and works, but loses Reality Composer Pro integration:
if let entity = try? await Entity(named: "test", in: Bundle.main)
Topic:
Spatial Computing
SubTopic:
Reality Composer Pro
Tags:
Xcode
Reality Converter
Reality Composer Pro
visionOS
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