What causes "context" in HangfireIO/Hangfire?

Construct a CreateContext with the required storage, connection, job, and initial state before calling Create.

HangfireIO/Hangfire · error · ArgumentNullException

context

Error message

context

What it means

Thrown by BackgroundJobFactory.Create when the CreateContext argument is null. Create is the entry point of the client-side job-creation pipeline: it resolves IClientFilter instances, sets context.Factory = this, and dispatches OnCreating/OnCreated around the inner factory. The null-guard prevents NREs deep in the filter-dispatch and serialization logic. Hangfire's own IBackgroundJobClient.Create path always builds a CreateContext, so a null context implies a custom client or test.

Source

Thrown at src/Hangfire.Core/Client/BackgroundJobFactory.cs:76

            }
        }

        internal BackgroundJobFactory(
            [NotNull] IJobFilterProvider filterProvider, 
            [NotNull] IBackgroundJobFactory innerFactory)
        {
            if (filterProvider == null) throw new ArgumentNullException(nameof(filterProvider));
            if (innerFactory == null) throw new ArgumentNullException(nameof(innerFactory));

            _filterProvider = filterProvider;
            _innerFactory = innerFactory;
        }

        public IStateMachine StateMachine => _innerFactory.StateMachine;

        public BackgroundJob Create(CreateContext context)
        {
            if (context == null) throw new ArgumentNullException(nameof(context));

            var filterInfo = GetFilters(context.Job);

            try
            {
                context.Factory = this;

                var createdContext = CreateWithFilters(context, filterInfo.ClientFilters);
                return createdContext.BackgroundJob;
            }
            catch (Exception ex) when (ex.IsCatchableExceptionType())
            {
                var exceptionContext = new ClientExceptionContext(context, ex);

                InvokeExceptionFilters(exceptionContext, filterInfo.ClientExceptionFiltersReversed);
                if (!exceptionContext.ExceptionHandled)
                {
                    throw;

View on GitHub (pinned to c236dd0f93)

Solutions

Construct a CreateContext with the required storage, connection, job, and initial state before calling Create.
Use the standard IBackgroundJobClient.Create path (e.g., BackgroundJob.Enqueue/ContinueWith/AddOrUpdate) which builds the context for you.
If you own a custom client, guard the context at your boundary and throw a descriptive exception.

Example fix

// before
var job = factory.Create(null);

// after
var createContext = new CreateContext(storage, connection, jobObj, initialState);
var job = factory.Create(createContext);

Defensive patterns

Strategy: validation

Validate before calling

if (createContext == null) throw new ArgumentException("CreateContext is required", nameof(createContext));
var job = factory.Create(createContext);

Type guard

public static bool IsValidCreateContext(CreateContext ctx)
    => ctx != null && ctx.Job != null && ctx.Storage != null;

Prevention

Use IBackgroundJobClient.Enqueue/AddOrUpdate/ContinueWith rather than calling factory.Create directly.
In custom clients, build a CreateContext with storage, connection, job, and initial state before invoking the factory.
Guard custom dispatch paths with a null check on the context.

When it happens

Trigger: Invoking factory.Create(null) directly; a custom IBackgroundJobClient implementation that calls the factory without building a CreateContext; unit tests stubbing the factory without a context.

Common situations: Replacing BackgroundJobClient with a custom wrapper; integration tests that short-circuit the client; DI misconfiguration returning a null context from a factory delegate.

Related errors

AI-assisted analysis of HangfireIO/Hangfire@c236dd0f93 (2026-08-13). Data as JSON: /api/errors/f653b1a6455a1213. Report an issue: GitHub.