Program.cs

usingSystem.Net;
usingSystem.Text.Json;
varbuilder=WebApplication.CreateBuilder();
builder.Services.AddSingleton<ErrorHandlingMiddleware>();

varapp=builder.Build();
app.UseMiddleware<ErrorHandlingMiddleware>();
app.Run(context =>thrownewExampleApiException("oops"));
app.Run();

publicinterfaceICustomApiException
{
HttpStatusCodeHttpStatus{get;}
stringHttpMessage{get;}
}

publicclassExampleApiException:Exception,ICustomApiException
{
publicHttpStatusCodeHttpStatus=>HttpStatusCode.Forbidden;
publicstringHttpMessage=>"Resource cannot be accessed.";

publicExampleApiException(stringmessage):base(message)
{
}
}

publicclassErrorDto
{
publicintStatus{get;set;}
publicstringMessage{get;set;}
}

publicclassErrorHandlingMiddleware:IMiddleware
{
privatereadonlyILogger<ErrorHandlingMiddleware>_logger;

publicErrorHandlingMiddleware(ILogger<ErrorHandlingMiddleware>logger)
{
_logger=logger;
}

publicasyncTaskInvokeAsync(HttpContextcontext,RequestDelegatenext)
{
try
{
awaitnext(context);
}
catch(Exceptionex)
{
_logger.LogError(ex,ex.Message);

varhttpStatus=HttpStatusCode.InternalServerError;
varhttpMessage="Internal Server Error";

if(exisICustomApiExceptioncustomException)
{
httpStatus=customException.HttpStatus;
httpMessage=customException.HttpMessage;
}

context.Response.StatusCode=(int)httpStatus;
context.Response.ContentType="application/json";

varerror=newErrorDto()
{
Status=(int)httpStatus,
Message=httpMessage
};

awaitcontext.Response.WriteAsync(JsonSerializer.Serialize(error));
}
}
}