"Resiliency" module / Implement code-based resiliency - JsonSerializationException instead of "The circuit is now open..." message

[AkosLukacs]

While doing the fifth step of the "resiliency" module https://learn.microsoft.com/en-us/training/modules/microservices-resiliency-aspnet-core/5-implement-polly-resiliency when testing the "Circuit Breaker policy", I got a Newtonsoft.Json.JsonSerializationException: Self referencing loop detected with type 'System.Text.RegularExpressions.Group'. Path 'captures'. instead of the expected "The circuit is now open..." message.

This is basically the last step of the linked page. Here are my screenshots from Seq, compare it with the one at the bottom of that step in the learn module:

Full json exception info:

{"@t":"2022-09-17T17:36:13.4987565Z","@mt":"An unhandled exception has occurred while executing the request.","@m":"An unhandled exception has occurred while executing the request.","@i":"bd577466","@l":"Error","@x":"Newtonsoft.Json.JsonSerializationException: Self referencing loop detected with type 'System.Text.RegularExpressions.Group'. Path 'captures'.\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CheckForCircularReference(JsonWriter writer, Object value, JsonProperty property, JsonContract contract, JsonContainerContract containerContract, JsonProperty containerProperty)\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IEnumerable values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)\n   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)\n   at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object value)\n   at Microsoft.AspNetCore.Mvc.Formatters.NewtonsoftJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)\n   at Microsoft.AspNetCore.Mvc.Formatters.NewtonsoftJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)\n   at Microsoft.AspNetCore.Mvc.Formatters.NewtonsoftJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()\n--- End of stack trace from previous location ---\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)\n   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)\n   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)\n   at Microsoft.AspNetCore.Authorization.Policy.AuthorizationMiddlewareResultHandler.HandleAsync(RequestDelegate next, HttpContext context, AuthorizationPolicy policy, PolicyAuthorizationResult authorizeResult)\n   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)\n   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)\n   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)\n   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)\n   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)","EventId":{"Id":1,"Name":"UnhandledException"},"SourceContext":"Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware","RequestId":"0HMKOQASG6LEH:00000003","RequestPath":"/webshoppingagg/api/v1/coupon/DISC-10","ConnectionId":"0HMKOQASG6LEH","ApplicationContext":"WebAggregator"}

[erjain]

Hi @AkosLukacs, thanks for raising the issue, we will review it and get back to you soon.