Tag Archives: error

eShopOnContainers – No parameterless constructor defined for type dbcontext

Hi everyone,

Another eShopOnContainers post. Today I was setting up migrations and ran into the following error:

Found DbContext ‘CatalogContext’.
Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type ‘CatalogContext’. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
—> System.MissingMethodException: No parameterless constructor defined for type ‘Catalog.Api.Infrastructure.CatalogContext’.
at System.RuntimeType.CreateInstanceDefaultCtorSlow(Boolean publicOnly, Boolean wrapExceptions, Boolean fillCache)

This turned out to be because I was missing the following from my CatalogContext:

public class CatalogContextDesignFactory : IDesignTimeDbContextFactory
public CatalogContext CreateDbContext(string[] args)
var optionsBuilder = new DbContextOptionsBuilder()
.UseSqlServer(“Server=.;Initial Catalog=Microsoft.eShopOnContainers.Services.CatalogDb;Integrated Security=true”);

return new CatalogContext(optionsBuilder.Options);

‘DatabaseFacade’ does not contain a definition for ‘Migrate’ and no accessible extension method ‘Migrate’… – eShopOnContainers

Hi everyone,

I’ve been going through Microsoft’s eShopOnContainers repo and replicating it as a small test project to learn microservices. While adding the WebHost Customization project I ran into the following error: 

Severity Code Description Project File Line Suppression State
Error CS1061 ‘DatabaseFacade’ does not contain a definition for ‘Migrate’ and no accessible extension method ‘Migrate’ accepting a first argument of type ‘DatabaseFacade’ could be found (are you missing a using directive or an assembly reference?) WebHost.Customization … N/A

This turned out to be a fairly simple fix. All that’s required is the following package (I installed via Nuget):


Thanks to the following stackoverflow post for the info: https://stackoverflow.com/a/57606203/522859

Return URL is missing path – Azure AD B2C

Hi everyone,

Just a small issue I’ve hit while implementing Azure AD B2C. After logging in Azure has been routing me to the base path instead of including the controller.

The solution to this turned out to be pretty straight-forward. All URLS apparently need to be including in the reply URLs of your Azure AD B2C application.

Just add a new row with the entire url to yours and it should start working immediately.


Azure AD B2C – Unauthorized

Hi everyone,

I’ve been mucking around with Azure AD B2C. It seems like a pretty good substitute for AWS Cognito that I’ve used previously.

While following the Microsoft sample tutorials I ran into an “unauthorized” error. A value was being returned but no access token was provided.

This seems to be indicative of an issue with scopes. In my case, I’d excluded a trailing slash on the ApiIdentifier url in the TaskWebApp web.config.

This seems to be a fairly common configuration issue. The following stackoverflow post pointed me in the right direction:


Relevant tutorial article can be found here: https://docs.microsoft.com/en-au/azure/active-directory-b2c/active-directory-b2c-tutorials-web-api?tabs=applications

error : “Timestamp” is not defined. – .net core and gRPC

Hi everyone,

I’m currently testing out gRPC with .NET Core and hit the following error when attempting to add a timestamp field to my proto file:

error : “Timestamp” is not defined.

My proto file was as follows:

syntax = “proto3”;
import “google/protobuf/timestamp.proto”;

option csharp_namespace = “publisher_api”;

package Weather;

// The weather forecast service definition
service Weather {

// Gets weather forecast
rpc Forecast(WeatherForecastRequest) returns (WeatherForecastResponse);

// The request message
message WeatherForecastRequest {


// The response message
message WeatherForecastResponse {
timestamp date = 1;
int32 temperatureC = 2;
int32 temperatureF = 3;
string summary = 4;

The solution was to fully qualify the timestamp namespace:

message WeatherForecastResponse {
google.protobuf.Timestamp date = 1;
int32 temperatureC = 2;
int32 temperatureF = 3;
string summary = 4;

Also ensure that you’ve added the protobuff package:

dotnet add package Google.Protobuf

See the following repo for a full example: https://github.com/Buzzology/microservicesDockerRabbitMQ

Current .NET SDK does not support targeting .NET Core 3.0 – Microservices

Hi everyone,

I’m currently learning microservices with .Net Core. As part of this I’ve been following one of Microsoft’s tutorials: https://dotnet.microsoft.com/learn/aspnet/microservice-tutorial

It has all been pretty straight forward, however I hit an error when attempting to run docker build:

RUN dotnet restore
—> Running in 734e82e92c23
/usr/share/dotnet/sdk/2.2.207/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.TargetFrameworkInference.targets(137,5): error NETSDK1045: The current .NET SDK does not support targeting .NET Core 3.0. Either target .NET Core 2.2 or lower, or use a version of the .NET SDK that supports .NET Core 3.0. [/src/myMicroservice.csproj]
The command ‘/bin/sh -c dotnet restore’ returned a non-zero code: 1

Updating the Dockerfile references seems to have resolved the issue. I replaced each occurrence of 2.2 with 3.0 and re-ran the following command:

docker build -t microservice .

My complete docker file was as follows:

# https://dotnet.microsoft.com/learn/aspnet/microservice-tutorial/docker-file
FROM mcr.microsoft.com/dotnet/core/sdk:3.0 AS build
COPY myMicroservice.csproj .
RUN dotnet restore
COPY . .
RUN dotnet publish -c release -o /app

FROM mcr.microsoft.com/dotnet/core/aspnet:3.0
COPY –from=build /app .
ENTRYPOINT [“dotnet”, “myMicroservice.dll”]

Full source available here: https://github.com/Buzzology/myMicroservice

Unable to create object of type ‘ApplicationDbContext’ – Updating to .NET Core 3.0

Hi everyone,

I’ve just updated to .net core 3.0 and have been hitting a few issues. I hit this one while trying to add a migration:

Unable to create an object of type ‘ApplicationDbContext’. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Adding -verbose to this allowed me to narrow the cause down a little further:

PM> add-migration add-propertyid-to-entities-for-events -verbose
Using project ‘PropertyApi’.
Using startup project ‘PropertyApi’.
Build started…
Build succeeded.
C:\Program Files\dotnet\dotnet.exe exec –depsfile C:\Users\Celeste\Documents\repos\property-api\PropertyApi\bin\Debug\netcoreapp3.0\PropertyApi.deps.json –additionalprobingpath C:\Users\Celeste\.nuget\packages –additionalprobingpath “C:\Program Files\dotnet\sdk\NuGetFallbackFolder” –runtimeconfig C:\Users\Celeste\Documents\repos\property-api\PropertyApi\bin\Debug\netcoreapp3.0\PropertyApi.runtimeconfig.json C:\Users\Celeste\.nuget\packages\microsoft.entityframeworkcore.tools\3.0.0\tools\netcoreapp2.0\any\ef.dll migrations add add-propertyid-to-entities-for-events –json –verbose –no-color –prefix-output –assembly C:\Users\Celeste\Documents\repos\property-api\PropertyApi\bin\Debug\netcoreapp3.0\PropertyApi.dll –startup-assembly C:\Users\Celeste\Documents\repos\property-api\PropertyApi\bin\Debug\netcoreapp3.0\PropertyApi.dll –project-dir C:\Users\Celeste\Documents\repos\property-api\PropertyApi\ –language C# –working-dir C:\Users\Celeste\Documents\repos\property-api –root-namespace PropertyApi
Using assembly ‘PropertyApi’.
Using startup assembly ‘PropertyApi’.
Using application base ‘C:\Users\Celeste\Documents\repos\property-api\PropertyApi\bin\Debug\netcoreapp3.0’.
Using working directory ‘C:\Users\Celeste\Documents\repos\property-api\PropertyApi’.
Using root namespace ‘PropertyApi’.
Using project directory ‘C:\Users\Celeste\Documents\repos\property-api\PropertyApi\’.
Finding DbContext classes…
Finding IDesignTimeDbContextFactory implementations…
Finding application service provider…
Finding Microsoft.Extensions.Hosting service provider…
Using environment ‘Development’.
System.ArgumentNullException: Value cannot be null. (Parameter ‘implementationInstance’)

The key part here are the fact that it can’t find the config values and that it’s attempting to use the ‘Development’ env whereas it should be looking for ‘Local’.

It seems that during the upgrade all of my environment variables have been wiped. All that was required was to run the following (change local to match your environment):


Running the add-migration command should now user the local configuration. Thanks to the following link for the solution:

Module not found: Can’t resolve ‘leaflet’ in – react-leaflet error

Hey everyone,

I ran into the following error after installing react-leaflet and attempting to run an example:

Module not found: Can’t resolve ‘leaflet’ in ‘…\node_modules\react-leaflet\es’

It turned out I’d simply rushed things and skipped the second step in the documentation:

npm install leaflet react react-dom # npm
yarn add leaflet react react-dom # Yarn

Doco: https://react-leaflet.js.org/docs/en/installation.html

NetTopologySuite Circular Reference with .net core 2.2

Hey everyone,

Testing out a spatial project with .net core and I ran into the following error:

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException : The best overloaded method match for ‘Xunit.Assert.Equal(string, string)’ has some invalid arguments

at CallSite.Target(Closure , CallSite , Type , Nullable`1 , Object )
at UpdateDelegates.UpdateAndExecuteVoid3[T0,T1,T2](CallSite site, T0 arg0, T1 arg1, T2 arg2)
at DiscussionsControllerIntegrationTests.CreateTestDiscussion(HttpClient client, ApplicationDbContext db, DiscussionCreateWebRequest payload) in DiscussionsControllerIntegrationTests.cs line: 56
at DiscussionsControllerIntegrationTests.b__1_0(ApplicationDbContext db) in DiscussionsControllerIntegrationTests.cs line: 27
at IntegrationTestBase.RunTest(Func`2 testToExecute) in IntegrationTestBase.cs line: 54
at DiscussionsControllerIntegrationTests.CreateDiscussionIsSuccessful() in DiscussionsControllerIntegrationTests.cs line: 25
at — End of stack trace from previous location where exception was thrown —

Thankfully the solution is pretty straight forward. Install GeoJSON:

Install-Package NetTopologySuite.IO.GeoJSON

Then merge the following with your existing addMvc call in startup.cs:

services.AddMvc(options =>
                // Prevent the following exception: 'This method does not support GeometryCollection arguments'
                // See: https://github.com/npgsql/Npgsql.EntityFrameworkCore.PostgreSQL/issues/585
                options.ModelMetadataDetailsProviders.Add(new SuppressChildValidationMetadataProvider(typeof(Point)));
                options.ModelMetadataDetailsProviders.Add(new SuppressChildValidationMetadataProvider(typeof(Coordinate)));
                options.ModelMetadataDetailsProviders.Add(new SuppressChildValidationMetadataProvider(typeof(LineString)));
                options.ModelMetadataDetailsProviders.Add(new SuppressChildValidationMetadataProvider(typeof(MultiLineString)));
                .AddJsonOptions(options =>
                    foreach (var converter in NetTopologySuite.IO.GeoJsonSerializer.Create(new GeometryFactory(new PrecisionModel(), 4326)).Converters)

Unable to find a dom node for 19 – Slate.js

Hi everyone,

I ran into the following error while attempting to add an image to a slate.js editor today:

slate.js unable to find dom node for 19

The solution was to add a simple schema to my editor:

const schema = {
    blocks: {
        image: {
            isVoid: true
    onFocus={() => { this.setState({ changed: true }); }}

There’s more on schemas in the official documentation: https://docs.slatejs.org/guides/schemas