abpframework/abp · error · Exception

Could not find an object of {typeof(T).AssemblyQualifiedName

Error message

Could not find an object of {typeof(T).AssemblyQualifiedName} in services. Be sure that you have used AddObjectAccessor before!

What it means

Thrown by ServiceCollectionObjectAccessorExtensions.GetObject<T> when no IObjectAccessor<T> has been registered (so the underlying value is null). The message reminds the caller to call AddObjectAccessor first. This is the read-side counterpart to error 233.

Source

Thrown at framework/src/Volo.Abp.Core/Microsoft/Extensions/DependencyInjection/ServiceCollectionObjectAccessorExtensions.cs:52

        }

        //Add to the beginning for fast retrieve
        services.Insert(0, ServiceDescriptor.Singleton(typeof(ObjectAccessor<T>), accessor));
        services.Insert(0, ServiceDescriptor.Singleton(typeof(IObjectAccessor<T>), accessor));

        return accessor;
    }

    public static T? GetObjectOrNull<T>(this IServiceCollection services)
        where T : class
    {
        return services.GetSingletonInstanceOrNull<IObjectAccessor<T>>()?.Value;
    }

    public static T GetObject<T>(this IServiceCollection services)
        where T : class
    {
        return services.GetObjectOrNull<T>() ?? throw new Exception($"Could not find an object of {typeof(T).AssemblyQualifiedName} in services. Be sure that you have used AddObjectAccessor before!");
    }
}

View on GitHub (pinned to 7ed43b1931)

Solutions

Register the accessor with AddObjectAccessor<T>() / TryAddObjectAccessor<T>() before calling GetObject<T>().
Use GetObjectOrNull<T>() if the value may legitimately be absent and handle the null case.
Reorder startup so the accessor is populated before dependent code reads it (often move the read into OnApplicationInitialization).

Example fix

// before — accessor never added
var cfg = services.GetObject<IConfiguration>();

// after — register first
services.AddObjectAccessor<IConfiguration>(myConfiguration);
var cfg = services.GetObject<IConfiguration>();
// or tolerate absence
var cfg = services.GetObjectOrNull<IConfiguration>();

Defensive patterns

Strategy: validation

Validate before calling

// Use the OrNull variant and register the accessor first when needed
var value = services.GetObjectOrNull<T>();
if (value == null)
{
    services.TryAddObjectAccessor<T>();
    // populate as needed, then read again
}

Prevention

Register the accessor (TryAddObjectAccessor) before reading it.
Use GetObjectOrNull<T>() when absence is acceptable.
Move reads into OnApplicationInitialization where accessors are populated.

When it happens

Trigger: Calling services.GetObject<T>() before any AddObjectAccessor<T>() has registered the accessor — e.g. reading IAbpHostEnvironment or IConfiguration during ConfigureServices before the host wired it.

Common situations: Accessing a framework accessor during module registration before the generic host has populated it; misordered startup; custom code resolving an accessor ABP never adds in the current hosting model.

Related errors

AI-assisted analysis of abpframework/abp@7ed43b1931 (2026-08-13). Data as JSON: /api/errors/d8044d28f1dba356. Report an issue: GitHub.