stride3d/stride · error · InvalidOperationException

The replacement asset can't be null when fixing a reference

Error message

The replacement asset can't be null when fixing a reference

What it means

ReferenceReplacementViewModel.FixReference throws InvalidOperationException (not an argument exception) when a replacement is requested but the ReplacementObject property is still null. The method decides between ClearReference and ReplaceReference based on whether a deletion or replacement is being fixed.

Solutions

1. Assign ReplacementObject to a valid asset before calling FixReference()
2. Force the clear-reference mode instead (ClearReference()) when no replacement is intended
3. Disable the fix action in the UI until a replacement is selected

Example fix

// before
viewModel.FixReference();
// after
if (viewModel.ReplacementObject == null)
    viewModel.ClearReference();
else
    viewModel.FixReference();

if (vm.ReplacementObject == null) { vm.ClearReference(); } else { vm.FixReference(); }

static bool HasReplacement([NotNullWhen(true)] object? r) => r is not null;

try { vm.FixReference(); } catch (InvalidOperationException ex) { logger.LogWarning(ex, "No replacement selected; clearing reference instead"); vm.ClearReference(); }

When it happens

Trigger: Calling FixReference() on a reference whose replacement mode is active while the user never picked a replacement asset (ReplacementObject == null).

Common situations: Clicking 'Fix' in the Fix References dialog without selecting a substitute asset, or programmatic fixing where the replacement was not assigned first.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• Invoking ShouldStayOpen before the work is finished.
• Container's value is null
• Could not find asset
• Expect name1=value1;name2=value2 format.
• assetItem must be an absolute path

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/effdee49efa594d6. Report an issue: GitHub.

Appendix: source

Thrown at sources/editor/Stride.Core.Assets.Editor/Components/FixReferences/ReferenceReplacementViewModel.cs:47

        public T Referencer { get; }

        public T ReplacementObject { get { return replacementObject; } set { SetValue(ref replacementObject, value, () => fixReferences.UpdateCommands()); } }

        public bool DontFixReference { get { return dontFixReference; } set { SetValue(ref dontFixReference, value, () => fixReferences.UpdateCommands()); } }

        public ICommandBase PickupReplacementObjectCommand { get; }

        public void FixReference()
        {
            if (DontFixReference)
            {
                ClearReference();
            }
            else
            {
                if (ReplacementObject == null)
                    throw new InvalidOperationException("The replacement asset can't be null when fixing a reference");

                ReplaceReference();
            }
        }

        public abstract void ClearReference();

        protected abstract void ReplaceReference();

        protected async Task PickupReplacementObject()
        {
            var replacement = await fixReferences.PickupObject(ObjectToFix, propertyType);
            if (replacement != null)
            {
                ReplacementObject = replacement;
            }
        }
    }

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