HangfireIO/Hangfire · error · ArgumentNullException

profiler

Error message

profiler

What it means

Thrown by the internal InvokeMeasured extension method on IProfiler when the profiler argument itself is null. This is a defensive precondition guard inside Hangfire's profiling infrastructure that wraps measured invocations. It signals a programming error inside the library or a custom IProfiler integration where a null profiler was passed rather than a real instance.

Source

Thrown at src/Hangfire.Core/Profiling/ProfilerExtensions.cs:29

// GNU Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public 
// License along with Hangfire. If not, see <http://www.gnu.org/licenses/>.

using System;
using Hangfire.Annotations;

namespace Hangfire.Profiling
{
    internal static class ProfilerExtensions
    {
        public static void InvokeMeasured<TInstance>(
            [NotNull] this IProfiler profiler,
            [CanBeNull] TInstance instance, 
            [NotNull] Action<TInstance> action,
            [CanBeNull] Func<TInstance, string> messageFunc = null)
        {
            if (profiler == null) throw new ArgumentNullException(nameof(profiler));
            if (action == null) throw new ArgumentNullException(nameof(action));

            profiler.InvokeMeasured(new InstanceAction<TInstance>(instance, action, messageFunc), InvokeAction, MessageCallback);
        }

        private static bool InvokeAction<TInstance>(InstanceAction<TInstance> tuple)
        {
            tuple.Action(tuple.Instance);
            return true;
        }

        private static string MessageCallback<TInstance>(InstanceAction<TInstance> action)
        {
            return action.MessageFunc?.Invoke(action.Instance);
        }

        internal struct InstanceAction<TInstance>
        {

View on GitHub (pinned to c236dd0f93)

Solutions

1. Ensure the IProfiler instance is non-null before calling InvokeMeasured — inject SlowLogProfiler or a custom profiler via DI.
2. If writing a custom IProfiler consumer, resolve the profiler from the same composition root as other Hangfire services rather than constructing it manually as null.
3. In tests, provide a real or mock IProfiler (e.g. new SlowLogProfiler(logger)) instead of null.

Example fix

// before
IProfiler profiler = null;
profiler.InvokeMeasured(instance, action);

// after
IProfiler profiler = new SlowLogProfiler(LogProvider.GetCurrentClassLogger());
profiler.InvokeMeasured(instance, action);

if (profiler == null) throw new InvalidOperationException("Profiler must be configured before invoking measured operations.");
profiler.InvokeMeasured(instance, action);

When it happens

Trigger: Calling profiler.InvokeMeasured(instance, action) where the 'profiler' variable (the 'this' target of the extension method) is null. This happens when a custom component injects or resolves a null IProfiler, or when a test/helper constructs a code path that bypasses profiler initialization.

Common situations: Writing a custom server process or filter that accepts an IProfiler dependency but receives null from a DI container misconfiguration. Unit testing internal Hangfire components without providing a profiler instance (e.g. null substituted for IProfiler).

Related errors

• action
• context
• filterProvider
• context
• exception

AI-assisted analysis of HangfireIO/Hangfire@c236dd0f93 (2026-08-13). Data as JSON: /api/errors/6573a8f0b9a43abb. Report an issue: GitHub.