Potential problems with 6.3.0

[esbenUnipluss]

Running a .net 6.0 C# Web API.

After upgrading Swashbuckle.AspNetCore from 6.2.3 to 6.3.0,
the API will not start, and gives the following error message:

Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Failed to generate Operation for action(ActionName) . See inner exception
---> Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Failed to generate schema for type(ActionType). See inner exception
---> System.NullReferenceException: Object reference not set to an instance of an object.
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForMember(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, DataProperty dataProperty)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateObjectSchema(DataContract dataContract, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass10_0.b__3()
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateReferencedSchema(DataContract dataContract, SchemaRepository schemaRepository, Func1 definitionFactory) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForMember(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, DataProperty dataProperty) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateObjectSchema(DataContract dataContract, SchemaRepository schemaRepository) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass10_0.<GenerateConcreteSchema>b__3() at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateReferencedSchema(DataContract dataContract, SchemaRepository schemaRepository, Func1 definitionFactory)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForType(Type modelType, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchema(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateArraySchema(DataContract dataContract, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass10_0.b__1()
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForMember(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, DataProperty dataProperty)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateObjectSchema(DataContract dataContract, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass10_0.b__3()
at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateReferencedSchema(DataContract dataContract, SchemaRepository schemaRepository, Func1 definitionFactory) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForType(Type modelType, SchemaRepository schemaRepository) at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchema(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo) at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateSchema(Type type, SchemaRepository schemaRepository, PropertyInfo propertyInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo) --- End of inner exception stack trace --- at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateSchema(Type type, SchemaRepository schemaRepository, PropertyInfo propertyInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo) at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.CreateResponseMediaType(ModelMetadata modelMetadata, SchemaRepository schemaRespository) at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.<>c__DisplayClass19_0.<GenerateResponse>b__2(String contentType) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable1 source, Func2 keySelector, Func2 elementSelector, IEqualityComparer1 comparer) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable1 source, Func2 keySelector, Func2 elementSelector)
at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateResponse(ApiDescription apiDescription, SchemaRepository schemaRepository, String statusCode, ApiResponseType apiResponseType)
at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateResponses(ApiDescription apiDescription, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperation(ApiDescription apiDescription, SchemaRepository schemaRepository)
--- End of inner exception stack trace ---
at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperation(ApiDescription apiDescription, SchemaRepository schemaRepository)
at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperations(IEnumerable1 apiDescriptions, SchemaRepository schemaRepository) at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePaths(IEnumerable1 apiDescriptions, SchemaRepository schemaRepository)a
at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwagger(String documentName, String host, String basePath)
at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)

by downgrading back to 6.2.3 it started working again.

I also have the Swashbuckle.AspNetCore.Newtonsoft installed - but any permutation of version 6.3.0 gives the same error message.

[domaindrivendev]

Thx for reporting this. Could you create an app (ideally as simple as possible) that repro’s the issue and post to GitHub. That way, I can pull down and it will be much easier to troubleshoot

[nielswitte]

Facing the same issue after upgrading from Swashbuckle.AspNetCore 6.2.3 to version 6.3.0. Also using Newtonsoft.

6.2.3 works fine.

[zsalkus]

@domaindrivendev adding the link to the app which reproduces the issue. it is caused by builder.Services.AddSwaggerGenNewtonsoftSupport() (l:6) in Program.cs due to enum in CrashObject.cs

https://github.com/zsalkus/Swashbuckle.AspNetCore.CrashDemo

[KnightSwordAG]

I am having the same issue with an API I also updated, but I'm not using Newtonsoft. Here's my error:

Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

System.MissingMethodException: Method not found: 'Microsoft.OpenApi.Models.OpenApiSchema Swashbuckle.AspNetCore.SwaggerGen.ISchemaGenerator.GenerateSchema(System.Type, Swashbuckle.AspNetCore.SwaggerGen.SchemaRepository, System.Reflection.MemberInfo, System.Reflection.ParameterInfo)'.
   at SignalRSwaggerGen.SignalRSwaggerGen.GetOpenApiSchema(DocumentFilterContext context, Type type)
   at SignalRSwaggerGen.SignalRSwaggerGen.<>c__DisplayClass8_0.<ToOpenApiParameters>b__0(ParameterInfo param)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.ToList()
   at SignalRSwaggerGen.SignalRSwaggerGen.AddOpenApiPath(OpenApiDocument swaggerDoc, DocumentFilterContext context, SignalRHubAttribute hubAttribute, String tag, String methodPath, Operation operation, String summary, String description, IEnumerable`1 methodParams, ParameterInfo methodReturnParam, MethodInfo method, MemberElement methodXml)
   at SignalRSwaggerGen.SignalRSwaggerGen.ProcessMethod(OpenApiDocument swaggerDoc, DocumentFilterContext context, SignalRHubAttribute hubAttribute, String hubPath, String tag, MethodInfo method, MemberElement methodXml)
   at SignalRSwaggerGen.SignalRSwaggerGen.ProcessHub(OpenApiDocument swaggerDoc, DocumentFilterContext context, Type hub, XmlComments xmlComments)
   at SignalRSwaggerGen.SignalRSwaggerGen.Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwagger(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.ResponseCompression.ResponseCompressionMiddleware.InvokeCore(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

I'm still investigating a cause, but the issue is ONLY from upgrading from 6.2.3 to 6.3.0.

[KnightSwordAG]

Okay, can confirm, this is unrelated. I can confirm that the issue is due to the SignalRSwaggerGen package. It doesn't play nice with the new Swashbuckle update. This is a red herring.

[manandre]

Same issue here with a Dictionary<TEnum, string>.
The regression has been introduced in #2166

Swashbuckle.AspNetCore/src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/SchemaGenerator.cs

Lines 91 to 94 in d63f028

	if (modelType.IsGenericType && modelType.GetGenericTypeDefinition() == typeof(Dictionary<,>))
	{
	schema.AdditionalProperties.Nullable = !memberInfo.IsDictionaryValueNonNullable();
	}

When the Keys of the dictionary are known, the schema.AdditionalPropertiesAllowed is false and then schema.AdditionalProperties is null, what indeed generates the NRE.

@Eneuman Can you please take a look at this specific case?

[Eneuman]

I'll take a look at this right away and make a PR for it.

[Eneuman]

Okay, can confirm, this is unrelated. I can confirm that the issue is due to the SignalRSwaggerGen package. It doesn't play nice with the new Swashbuckle update. This is a red herring.

@KnightSwordAG It looks like that package is using a dictionary with known keys so this might be related to this.
SignalRSwaggerGen.<>c__DisplayClass8_0.<ToOpenApiParameters>b__0