HangfireIO/Hangfire · error · ArgumentNullException

owinEnvironment

Error message

owinEnvironment

What it means

The obsolete UrlHelper constructor taking an OWIN environment dictionary (UrlHelper.cs:30) throws ArgumentNullException when owinEnvironment is null. The constructor wraps the dictionary in an OwinContext for request path resolution. This overload is deprecated in favor of UrlHelper(DashboardContext).

Source

Thrown at src/Hangfire.Core/Dashboard/UrlHelper.cs:30

// 
// 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 System.Collections.Generic;
using Hangfire.Annotations;

namespace Hangfire.Dashboard
{
    public class UrlHelper
    {
#if FEATURE_OWIN
        private readonly Microsoft.Owin.OwinContext _owinContext;

        [Obsolete("Please use UrlHelper(DashboardContext) instead. Will be removed in 2.0.0.")]
        public UrlHelper([NotNull] IDictionary<string, object> owinEnvironment)
        {
            if (owinEnvironment == null) throw new ArgumentNullException(nameof(owinEnvironment));
            _owinContext = new Microsoft.Owin.OwinContext(owinEnvironment);
        }
#endif

        private readonly DashboardContext _context;

        public UrlHelper([NotNull] DashboardContext context)
        {
            if (context == null) throw new ArgumentNullException(nameof(context));
            _context = context;
        }

        public string To(string relativePath)
        {
            return _context.Options.PrefixPath +
                   (
#if FEATURE_OWIN
                       _owinContext?.Request.PathBase.Value ??

View on GitHub (pinned to c236dd0f93)

Solutions

1. Migrate to the UrlHelper(DashboardContext) constructor which is the supported API.
2. If keeping the OWIN overload, ensure the environment dictionary is non-null.

Example fix

// before (obsolete OWIN overload)
var helper = new UrlHelper(owinEnv); // owinEnv may be null

// after (supported overload)
var helper = new UrlHelper(dashboardContext);

if (owinEnvironment == null)
    throw new ArgumentNullException(nameof(owinEnvironment));
var helper = new UrlHelper(owinEnvironment);

When it happens

Trigger: Instantiating new UrlHelper(null) via the OWIN dictionary overload, or passing a variable that resolved to null.

Common situations: Legacy OWIN-based dashboard middleware passing a null environment; migrating from OWIN to ASP.NET Core and the environment dictionary is no longer available.

Related errors

• app
• owinEnvironment
• routes
• pathTemplate
• context

AI-assisted analysis of HangfireIO/Hangfire@c236dd0f93 (2026-08-13). Data as JSON: /api/errors/680d02d2d6825a2a. Report an issue: GitHub.