dotnet/BenchmarkDotNet · error · ArgumentNullException

{name} can't be null

Error message

{name} can't be null

What it means

Assertion.NotNull is an internal assertion helper annotated with [AssertionMethod]. It throws ArgumentNullException with message "{name} can't be null" when value is null. It is used internally to fail fast on null invariants the library depends on; the message text is a thin wrapper over ArgumentNullException.

Source

Thrown at src/BenchmarkDotNet/Helpers/Assertion.cs:11

using JetBrains.Annotations;

namespace BenchmarkDotNet.Helpers;

internal static class Assertion
{
    [AssertionMethod]
    public static void NotNull(string name, object? value)
    {
        if (value == null)
            throw new ArgumentNullException(name, $"{name} can't be null");
    }
}

View on GitHub (pinned to b515068b61)

Solutions

1. Inspect the stack trace to find which internal contract was violated and the originating config/setup.
2. Ensure all required benchmark setup objects (attributes, configs, jobs) are fully specified.
3. If state looks correct, report a BenchmarkDotNet issue with the reproduction; this asserts an internal invariant.

try { /* setup/run */ }
catch (ArgumentNullException ex) when (ex.Message.Contains("can't be null")) { /* inspect stack, report library issue */ }

When it happens

Trigger: An internal BenchmarkDotNet code path calls Assertion.NotNull(name, value) and value is null, indicating a violated precondition (e.g. a required descriptor, job, or report object was unexpectedly null).

Common situations: A previous step failed to produce a required object (a benchmark case missing a descriptor, a job without a runtime), corrupted/incomplete state, or a library bug where an internal contract was not upheld.

Related errors

• Value cannot be null. (Parameter 'values')
• 'source' cannot be null or whitespace.
• Missing extension on source '{source}', must have the extens
• Unsupported extension on source '{source}', must have the ex
• The value {value} is not assignable to {characteristic} prop

AI-assisted analysis of dotnet/BenchmarkDotNet@b515068b61 (2026-08-13). Data as JSON: /api/errors/9c00c1a838b0329a. Report an issue: GitHub.