stride3d/stride · error · ArgumentNullException

ArgumentNullException: generator

Error message

ArgumentNullException: generator

What it means

RunTemplateGeneratorSafe runs an ITemplateGenerator<TParameters> safely with progress reporting, and validates its arguments up front. It throws ArgumentNullException when the generator parameter is null — no template generator was supplied to run.

Solutions

1. Pass a non-null ITemplateGenerator<TParameters> instance
2. Verify the generator factory/resolution logic never returns null for known templates
3. Check that the template being generated has a registered generator implementation

Example fix

// before
await TemplateGeneratorHelper.RunTemplateGeneratorSafe(generator, parameters, progress);
// after
if (generator == null) throw new InvalidOperationException($"No generator found for template '{parameters?.TemplateId}'");
await TemplateGeneratorHelper.RunTemplateGeneratorSafe(generator, parameters, progress);

if (generator == null) throw new ArgumentException("No template generator resolved for this template", nameof(generator));

bool CanRun<T>(ITemplateGenerator<T> g) where T : TemplateGeneratorParameters => g != null;

try { await RunTemplateGeneratorSafe(generator, parameters, progress); } catch (ArgumentNullException ex) when (ex.ParamName == "generator") { /* report missing generator for template */ }

When it happens

Trigger: Calling TemplateGeneratorHelper.RunTemplateGeneratorSafe(null, parameters, workProgress), e.g. when the generator factory or template resolution returned null before the call.

Common situations: Template descriptor not matching any registered generator; DI/factory returning null for an unknown or misconfigured template; refactoring that removed a generator registration.

Related errors

• ArgumentNullException: parameters
• builder
• Cannot add a null UIElement to the children list.
• compilerParameters
• gameSettings

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/e45cfd61482f1fc9. Report an issue: GitHub.

Appendix: source

Thrown at sources/editor/Stride.Core.Assets.Editor/Components/TemplateDescriptions/TemplateGeneratorHelper.cs:24

using Stride.Core.Assets.Editor.ViewModel.Progress;
using Stride.Core.Assets.Templates;
using Stride.Core.Translation;

namespace Stride.Core.Assets.Editor.Components.TemplateDescriptions
{
    internal static class TemplateGeneratorHelper
    {
        /// <summary>
        /// Invokes the given template generator safely. The generator will be prepared on the calling thread, and run from
        /// a task. This methods will catch and log all exceptions occurring during the template generation.
        /// </summary>
        /// <param name="generator">The template generator to run.</param>
        /// <param name="parameters">The parameters for the template generator.</param>
        /// <param name="workProgress">The view model used to report progress.</param>
        /// <returns>A task that completes when the template generator has finished to run.</returns>
        internal static async Task<bool> RunTemplateGeneratorSafe<TParameters>(ITemplateGenerator<TParameters> generator, TParameters parameters, WorkProgressViewModel workProgress) where TParameters : TemplateGeneratorParameters
        {
            if (generator == null) throw new ArgumentNullException(nameof(generator));
            if (parameters == null) throw new ArgumentNullException(nameof(parameters));
            var success = false;
            try
            {
                success = await generator.PrepareForRun(parameters);
                if (!success)
                {
                    // If the preparation failed without error, it means that the user cancelled the operation.
                    if (!parameters.Logger.HasErrors)
                        parameters.Logger.Info(Tr._p("Log", "Operation cancelled."));

                    return false;
                }
            }
            catch (Exception e)
            {
                parameters.Logger.Error(Tr._p("Log", "An exception occurred while generating the template."), e);
            }

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