dotnet/BenchmarkDotNet · error · ArgumentException

String cannot be empty.

Error message

String cannot be empty.

What it means

Thrown by the ThrowIfNullOrEmpty polyfill in BenchmarkDotNet.Extensions.ArgumentExceptionExtensions. It mirrors ArgumentException.ThrowIfNullOrEmpty: a null argument raises ArgumentNullException first, then a zero-length string raises this ArgumentException ("String cannot be empty."). The library uses it to validate string-shaped configuration and identifier arguments internally.

Source

Thrown at src/BenchmarkDotNet/Extensions/Polyfills/ArgumentExceptionExtensions.cs:19

#if NET6_0 || NETSTANDARD2_0
using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;

namespace System;

internal static partial class ArgumentExceptionExtensions
{
    extension(ArgumentException)
    {
        public static void ThrowIfNullOrEmpty(
            string? argument,
            [CallerArgumentExpression(nameof(argument))] string? paramName = null)
        {
            if (argument is null)
                throw new ArgumentNullException(paramName);

            if (argument.Length == 0)
                throw new ArgumentException("String cannot be empty.", paramName);
        }

        public static void ThrowIfNullOrWhiteSpace([NotNull] string? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
        {
            if (argument is null)
            {
                throw new ArgumentNullException(paramName);
            }

            if (string.IsNullOrWhiteSpace(argument))
            {
                throw new ArgumentException("String cannot be empty or whitespace.", paramName);
            }
        }
    }
}
#endif

View on GitHub (pinned to b515068b61)

Solutions

1. Supply a non-empty, meaningful string value to the configuration property that triggered it.
2. If the value is optional, pass null (most validated APIs accept nullable) rather than an empty string.
3. Trace the stack trace to the BenchmarkDotNet call site and pre-validate the originating config field with string.IsNullOrEmpty before assignment.

Example fix

// before
config.ArtifactsPath = "";

// after
config.ArtifactsPath = "./benchmark-results";

if (string.IsNullOrEmpty(value)) throw new InvalidOperationException("value must be non-empty");
// or: guard the assignment to the BenchmarkDotNet config field

When it happens

Trigger: Any internal BenchmarkDotNet call site invokes ArgumentException.ThrowIfNullOrEmpty(value) and the supplied string has Length == 0 (e.g. an empty artifacts path, empty job id, or empty column name passed into a validated API).

Common situations: Empty ArtifactsPath or output template, empty argument/property names, programmatic config that defaults an optional string to "" instead of null, or reading an unset environment/config value that resolves to an empty string.

Related errors

• String cannot be empty or whitespace.
• Property name must be non-empty.
• The value {value} is not assignable to {characteristic} prop
• Runtime Moniker not supported
• Please use job.Env.Jit to specify Jit in explicit way

AI-assisted analysis of dotnet/BenchmarkDotNet@b515068b61 (2026-08-13). Data as JSON: /api/errors/08d15e587f338adb. Report an issue: GitHub.