gfx-rs/wgpu · error

COM pointer should not be NULL

Error message

COM pointer should not be NULL

What it means

Panic in the DX12 backend's create_surface_from_visual: the passed raw pointer for the Windows UI Composition visual is NULL, so the DCompositionSurface cannot be retrieved. The faulty input is the null visual pointer.

Source

Thrown at wgpu-hal/src/dx12/mod.rs:442

    supports_allow_tearing: bool,
    presentation_system: wgt::Dx12SwapchainKind,
    _lib_dxgi: DxgiLib,
    flags: wgt::InstanceFlags,
    memory_budget_thresholds: wgt::MemoryBudgetThresholds,
    compiler_container: Arc<shader_compilation::CompilerContainer>,
    options: wgt::Dx12BackendOptions,
    telemetry: Option<crate::Telemetry>,
}

impl Instance {
    /// Get the raw DXGI factory associated with this instance.
    pub unsafe fn raw_factory4(&self) -> &Dxgi::IDXGIFactory4 {
        self.factory.deref()
    }

    pub unsafe fn create_surface_from_visual(&self, visual: *mut ffi::c_void) -> Surface {
        let visual = unsafe { DirectComposition::IDCompositionVisual::from_raw_borrowed(&visual) }
            .expect("COM pointer should not be NULL");
        Surface {
            factory: self.factory.clone(),
            factory_media: self.factory_media.clone(),
            target: SurfaceTarget::Visual(visual.to_owned()),
            supports_allow_tearing: self.supports_allow_tearing,
            swap_chain: RwLock::new(None),
            options: self.options.clone(),
            hdr_source: None,
        }
    }

    pub unsafe fn create_surface_from_surface_handle(
        &self,
        surface_handle: *mut ffi::c_void,
    ) -> Surface {
        // TODO: We're not given ownership, so we shouldn't call HANDLE::free(). This puts an extra burden on the caller to keep it alive.
        // https://learn.microsoft.com/en-us/windows/win32/api/handleapi/nf-handleapi-duplicatehandle could help us, even though DirectComposition is not in the list?
        // Or we make all these types owned, require an ownership transition, and replace SurfaceTargetUnsafe with SurfaceTarget.

View on GitHub (pinned to 3e11ff59bf)

Solutions

1. Pass a valid non-null IDCompositionVisual pointer when creating the surface
2. Check the pointer before calling the unsafe constructor

When it happens

Trigger: Thrown at wgpu-hal/src/dx12/mod.rs:442 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of gfx-rs/wgpu@3e11ff59bf (2026-09-03). Data as JSON: /api/errors/e77cc6e22b8c9fc5. Report an issue: GitHub.