abpframework/abp · error · AbpException

serviceKey can not be null! Use ExposeServicesAttribute inst

Error message

serviceKey can not be null! Use ExposeServicesAttribute instead.

What it means

Thrown by the ExposeKeyedServiceAttribute<TServiceType> constructor (generic form) when the serviceKey argument is null. ABP tells you to use ExposeServicesAttribute instead, because a null key has no meaning for keyed service registration. It is an AbpException.

Source

Thrown at framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ExposeKeyedServiceAttribute.cs:15

using System;

namespace Volo.Abp.DependencyInjection;

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
public class ExposeKeyedServiceAttribute<TServiceType> : Attribute, IExposedKeyedServiceTypesProvider
    where TServiceType : class
{
    public ServiceIdentifier ServiceIdentifier { get; }

    public ExposeKeyedServiceAttribute(object serviceKey)
    {
        if (serviceKey == null)
        {
            throw new AbpException($"{nameof(serviceKey)} can not be null! Use {nameof(ExposeServicesAttribute)} instead.");
        }

        ServiceIdentifier = new ServiceIdentifier(serviceKey, typeof(TServiceType));
    }

    public ServiceIdentifier[] GetExposedServiceTypes(Type targetType)
    {
        return new[] { ServiceIdentifier };
    }
}

View on GitHub (pinned to 7ed43b1931)

Solutions

Pass a concrete non-null key (a string, enum, or object) to the attribute.
If you do not need keying at all, switch to [ExposeServices(typeof(TService))].
If the key comes from a constant, ensure the constant is initialized and non-null.

Example fix

// before
[ExposeKeyedServiceAttribute<IMyService>(null)]
public class MyService : IMyService { }

// after
[ExposeKeyedServiceAttribute<IMyService>("primary")]
public class MyService : IMyService { }

Defensive patterns

Strategy: validation

Validate before calling

// Attributes are compile-time; 'validate' by never passing null.
// Use a real key literal or switch to ExposeServicesAttribute.

Try / catch

try { /* attribute ctor runs at reflection time */ }
catch (AbpException ex) when (ex.Message.Contains("serviceKey"))
{
    logger.LogError(ex, "Keyed service attribute misconfigured on {Type}", type);
}

Prevention

Always pass a concrete key (string/enum/object) to ExposeKeyedServiceAttribute.
If you do not need keying, use [ExposeServices(typeof(T))] instead.
Avoid [ExposeKeyedServiceAttribute<T>(someField)] where someField could be null.

When it happens

Trigger: Decorating a class with [ExposeKeyedServiceAttribute<TService>(null)] or passing a null-typed constant/field as serviceKey at the attribute level.

Common situations: Mistakenly passing null (or an uninitialized static field) as the keyed-service key, or confusing the keyed attribute with the non-keyed ExposeServicesAttribute.

Related errors

AI-assisted analysis of abpframework/abp@7ed43b1931 (2026-08-13). Data as JSON: /api/errors/48250e2736f51217. Report an issue: GitHub.