Questions tagged [.net-core]
.NET Core is an open-source successor of the .NET Framework. It can be used in a wide variety of applications and verticals, ranging from servers and data centers to apps and devices. .NET Core is supported by Microsoft on Windows, Linux and macOS.
.net-core
45,017
questions
72
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Safety of AsyncLocal in ASP.NET Core
For .NET Core, AsyncLocal is the replacement for CallContext. However, it is unclear how "safe" it is to use in ASP.NET Core.
In ASP.NET 4 (MVC 5) and earlier, the thread-agility model of ASP.NET ...
- 29.7k
71
votes
1
answer
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Cascade deleting with EF Core
I am having a few issues with EF Core at the moment. I have some data that I need to delete, and I am struggeling to see how the fluent API works, exactly in regards to the .OnDelete() function.
...
- 3,074
71
votes
10
answers
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Nuget restore fails on Azure Devops with message "unable to load the service index for source"
I have a build for a .NET solution that is running in a private agent. The solution contains both .NET Core 2.1 and .NET Standard 2.0 projects.
Some of the nuget packages installed are the following:...
- 11.5k
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votes
14
answers
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Where is the PostAsJsonAsync method in ASP.NET Core?
I was looking for the PostAsJsonAsync() extension method in ASP.NET Core. Based on this article, it's available in the Microsoft.AspNet.WebApi.Client assembly.
I had thought Microsoft had changed ...
- 32.3k
70
votes
13
answers
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Enable OPTIONS header for CORS on .NET Core Web API
I solved this problem after not finding the solution on Stackoverflow, so I am sharing my problem here and the solution in an answer.
After enabling a cross domain policy in my .NET Core Web Api ...
- 3,273
70
votes
8
answers
48k
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How to Unit Test with ActionResult<T>?
I have a xUnit test like:
[Fact]
public async void GetLocationsCountAsync_WhenCalled_ReturnsLocationsCount()
{
_locationsService.Setup(s => s.GetLocationsCountAsync("123")).ReturnsAsync(10);
...
- 5,592
70
votes
11
answers
169k
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Postman error: "Unable to verify the first certificate" when try to get from my .net core API
I have my brand new .NET Core service with API and I want to get list of items inside it. It's hosted on localhost and I always have this error:
16 ms
Warning: Unable to verify the first certificate
...
- 687
69
votes
11
answers
73k
views
Failed to find a valid digest in the 'integrity' attribute for resource in Blazor app
I have a Blazor client/server app that I have been working on for a period and it has been working fine up to now. I suddenly started getting this error
Failed to find a valid digest in the '...
- 935
69
votes
1
answer
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Difference between AllowedHosts in appsettings.json and UseCors in .NET Core API 3.x
I see that .NET Core 3.x comes with a new special configuration AllowedHosts used to list hosts allowed to access the site while this option already exists with CORS (app.UseCors).
What's the ...
- 793
69
votes
4
answers
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How to run all tests in Visual Studio Code
The latest version of VS Code already provides an easy way of running a single test as pointed on Tyler Long's answer to the question Debugging xunit tests in .NET Core and Visual Studio Code.
However,...
- 9,043
68
votes
14
answers
119k
views
EF Core Error - No project was found. Change the current working directory or use the --project option
I am using Visual Studio 2015 and dotnet core and trying to develop an EF Core Code First project using Sqlite and this documentation / tutorial, which also uses Sqlite => NET Core - New Database
...
- 20.8k
68
votes
3
answers
15k
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No UseDatabaseErrorPage() extension method in Net Core 3.0
I have created Net Core 3.0 app and following code that worked in 2.2 now is not.
app.UseDatabaseErrorPage();
Looks like in 3.0 class DatabaseErrorPageExtensions does not exist within Microsoft....
- 1,130
68
votes
11
answers
82k
views
Error: It was not possible to find any installed .NET Core SDKs
When I run the command docker run -i -t myProject it shows error:
It was not possible to find any installed .NET Core SDKs
Did you mean to run .NET Core SDK commands? Install a .NET Core SDK ...
- 681
68
votes
15
answers
51k
views
Looking for simple rules-engine library in .NET [closed]
Does anyone know of a good .NET library rules library (ideally open-source)? I need something that can do nested logic expressions, e.g., (A AND B) AND (B OR C OR D). I need to do comparisons of ...
- 681
68
votes
1
answer
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Which web server are you using in production for ASP.NET Core on a *nix server?
With ASP.NET Core now released, I was wondering what the best hosting option is for Linux and Mac environments. Is there any production grade web server under active development?
The only one I'm ...
- 6,420
67
votes
7
answers
18k
views
Problems installing Dot Net Core 1.0.0 VS 2015 Tools Preview 2
Each time I try to install the DotNetCore.1.0.0-VS2015Tools.Preview2.exe package I get an error saying the following:
Setup Failed One or more issues caused the setup to fail. Please fix
the ...
- 1,546
67
votes
2
answers
67k
views
System.Text.Json: How do I specify a custom name for an enum value?
Using the System.Text.Json serializer capabilities in .NET Core, how can I specify a custom value for an enum value, similar to JsonPropertyName? For example:
public enum Example {
Trick,
Treat, ...
- 3,627
67
votes
7
answers
160k
views
How do I resolve the issue the request matched multiple endpoints in .Net Core Web Api
I notice that there are a bunch of similar questions out there about this topic.
I'm getting this error when calling any of the methods below.
Microsoft.AspNetCore.Routing.Matching....
- 1,479
67
votes
5
answers
60k
views
Use Serilog with Microsoft.Extensions.Logging.ILogger
I've created a .NET Core 3.1 project using a Host, the IoC container with IServiceCollection and implemented logging allover the place using the ILogger<T> interface from Microsoft.Extensions....
- 1,242
67
votes
7
answers
42k
views
Is there a way to format the output format in .NET Core logging?
I'm using the built in logging provider for logging into the console (Microsoft.Extensions.Logging.Console) in a .NET Core console application.
Each logging entry produces two lines in the output. I ...
- 917
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votes
3
answers
39k
views
.Net Core and NuGet
I installed .net core from this site. Playing with it led to a number of related package management questions:
The dotnet restore command proceeded to "install" .net core NuGet packages. Where were ...
- 29.7k
67
votes
1
answer
3k
views
Why are three properties in DbParameterCollection abstract in reference assemblies but virtual otherwise?
I'm moving a project from project.json to the new-style csproj format, and it includes a class derived from DbParameterCollection. In my real project I'm using multi-targeting, but for the purposes of ...
- 1.5m
66
votes
7
answers
43k
views
How to fix obsolete ILoggerFactory methods?
I upgraded my project to .NET Core 2.2.x and got an obsolete warning regarding the following code - both lines:
public void Configure(IApplicationBuilder app,
...
- 60.5k
66
votes
7
answers
113k
views
Access from class library to appsetting.json in Asp.net-core
I am trying to access appsetting.json file from a class library. So far the solution that I found is to create a configuration class implementing interface IConfiguration from Microsoft.Extensions....
- 3,012
66
votes
1
answer
18k
views
Upgrading to .NET Core 2.0: PackageTargetFallback and AssetTargetFallback cannot be used together
When upgrading a project that is compiling and running fine on .NET Core 1.0 or 1.1, updating the target framework to .NET Core 2.0 (netcoreapp2.0) causes the build to fail with the following error:
...
- 97.6k
65
votes
5
answers
51k
views
How to set .NET Core in #if statement for compilation
I created a multi-targeted framework project. I use something like this:
#if NET40
Console.WriteLine("Hello from .NET Core 4");
#endif
But I can't find a wildcard for .NET Core. I tried:
...
- 1,303
65
votes
2
answers
27k
views
Difference between .NET Framework 4.6, .Net Native and .Net Core [closed]
I see the following in almost every future .NET framework discussion:
.NET Framework 4.6 (Full .Net framework)
.NET Native
.NET Core
What is the difference between all of these?
How do I know when ...
- 7,045
65
votes
4
answers
170k
views
Reference external DLL in .NET Core project
I've my own .dll file that I used to use with Edge.js in nodejs,
I'm trying to use it now with dot net core app, but found no where/no how to get access to it, or define it.
is there something like
...
- 23.9k
65
votes
3
answers
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views
How is the new C# Span<T> different from ArraySegment<T>?
I am having trouble conceptualizing the usages for the new Span<T> in C#.
What construct(s) does it replace? Is ArraySegment<T> now obsolete?
What functionality does it enable that ...
- 3,264
65
votes
6
answers
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views
How do I add assembly references in Visual Studio Code?
So I've come across a similar issue twice now while working on my first project in C#. When trying to add either using System.Data; or using System.Timers;, I get the following error:
The type or ...
- 941
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votes
3
answers
48k
views
Filter Serilog logs to different sinks depending on context source?
I have a .NET Core 2.0 application in which I successfully use Serilog for logging. Now, I would like to log some database performance statistics to a separate sink (they are not for debugging, which ...
- 12.8k
64
votes
8
answers
32k
views
Build error while transitioning between branches: Your project is not referencing the ".NETFramework,Version=v4.7.2" framework
We're using Git and we have a solution which is targeting the full net framework. A couple of days ago, I've started migrating the solution to .net core. Unfortunately, something comes up which made ...
- 4,162
64
votes
16
answers
141k
views
Failed to bind to address (already in use) error with Visual Studio Mac API
I'm attempting to create a Web API via .Net Core. I'm just using the boilerplate ValuesController as a Hello World. When I run the project, I get the following error:
System.IO.IOException: "Failed ...
- 1,931
64
votes
11
answers
109k
views
Get List<> element position in c# using LINQ
I have a List with numbers,
and I'd like to find the position of the minimum (not value) using LINQ
Example:
var lst = new List<int>() { 3, 1, 0, 5 };
Now I am looking for a function returning ...
newUser
64
votes
10
answers
87k
views
CORS in .NET Core
I am trying to enable CORS in .NET Core in this way:
public IConfigurationRoot Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services....
- 1,285
64
votes
3
answers
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views
Should GetEnvironmentVariable work in xUnit tests?
If I set environment variables for a .Net Core web project in Visual Studio 2017 using the project properties page, I can read the value of the variable using Environment.GetEnvironmentVariable; ...
- 2,240
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votes
9
answers
108k
views
Receive file and other form data together in ASP.NET Core Web API (boundary based request parsing)
How would you form your parameters for the action method which is supposed to receive one file and one text value from the request?
I tried this
public string Post([FromBody]string name, [FromBody]...
- 7,915
64
votes
8
answers
49k
views
dotnet publish with /p:PublishProfile=?
I'm trying to call "dotnet publish" with a specific publish profile pubxml file as documented here :
https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/visual-studio-publish-profiles?view=...
- 1,258
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votes
9
answers
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views
Is it possible to run a .NET Core console application silently (hide console window)?
I'm trying to automate some tasks for myself and I wrote a few .NET Core 1.0 console applications. One of them is BrowserRouter - a simple application which, based on a URL pattern, decides which ...
- 661
63
votes
13
answers
25k
views
No executables found matching command 'dotnet-aspnet-codegenerator'"
When trying to add a Controller in an ASP.NET Core project using Visual Studio 15 Enterprise with Update 3, I get the error below:
"The was an error running the selected code generator: No ...
- 1,380
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votes
10
answers
57k
views
Error in Visual Studio Code Dotnet Core C#: "The type or namespace name 'System' could not be found", but build succeeds
When trying to work with Visual Studio Code on a C# DotNet Core MVC application, I am having a lot of trouble getting visual studio code to work. It is having trouble finding anything related to C#, ...
- 725
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votes
5
answers
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views
Access to configuration without dependency injection
I was wondering if there was a way to access Configuration (Microsoft.Extensions.Configuration) without the use of dependency injection. Only examples I see are through constructor injection (using ...
- 2,111
63
votes
1
answer
10k
views
Dotnet Core Docker Container Leaks RAM on Linux and causes OOM
I am running Dotnet Core 2.2 in a Linux container in Docker.
I've tried many different configuration/environment options - but I keep coming back to the same problem of running out of memory ('docker ...
- 631
62
votes
2
answers
63k
views
How to run .NET Core Console app using generic host builder
I am trying to figure out how to use hostbuilder pattern to run a console app (not a windows service). Intent is to keep the flow as similar to a WebApi to keep development practices similar. I have ...
- 1,546
62
votes
3
answers
65k
views
Unable to resolve service for type 'System.String' while attempting to activate 'MyService'
I'm seeing the following exception in my Service Fabric Stateless ASP.NET Core app.
System.InvalidOperationException: Unable to resolve service for type 'System.String' while attempting to activate '...
- 15.4k
61
votes
3
answers
75k
views
Nuget - Package restore failed. Rolling back package changes for 'WebApplication1'. 0
It's my own custom nuget package that I've not published yet and testing locally.
The nuget package consists of a dll file and nuspec file is as follows.
<?xml version="1.0"?>
<package >
...
- 7,210
61
votes
9
answers
70k
views
You must add a reference to assembly mscorlib, version=4.0.0
I'm having some trouble migrating a web project from RC1 to RC2. When I switched, I'm getting a bunch of these errors throughout the project.
The type 'Func<,>' is defined in an assembly that is ...
- 2,639
61
votes
9
answers
62k
views
Cross-platform file name handling in .NET Core
How to handle file name in System.IO classes in a cross-platform manner to make it work on Windows and Linux?
For example, I write this code that works perfectly on Windows, however it doesn't create ...
- 12k
61
votes
22
answers
55k
views
System could not be found Visual Studio 2017 ASP.NET Core project
I've installed the newly released version of Visual Studio 2017 and started a fresh ASP.NET Core project targeting .NET Core.
Out of the box, I'm getting the
The type or namespace name 'System' ...
- 28.4k
61
votes
1
answer
26k
views
How to determine if service has already been added to IServiceCollection
I am creating helper classes to simplify configuration and injection of interfaces via IServiceCollection for a library. The libraries constructor contains a number of dependencies that are likely to ...
- 611