Cannot access a disposed object in ASP.NET Core when injecting DbContext

Find the root cause of what really happened to you disposable object.


Working with ASP.NET core I have seen this error multiple times and can be hard to debug. The error can have multiple root causes. It can be a real pain to find the cause and it is sometimes fixed by only taking care of the symptoms. By finding the root cause, you can take the appropriate action in your code.

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Set custom timeout for code first Migrations Entity Framework (Core 2.0)

Allow customizing timeout for migrations.

Sometimes a migration takes more time then your default timeout of your database connection. In such a case you do want to increase the timeout for the migration to be able to complete, but you do not want to change the timeout for your normal operations.
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Add Index with Include Entity Framework (Core 2.0)

Add index with inlude in EF Core 2.0 code first migrations

When creating indexes with code first migrations in Entity Framework Core 2.0 you can create an index on a table by adding the following to your DbContext:

protected override void OnModelCreating(ModelBuilder modelBuilder)

        .HasIndex(t => new { rrs.Column1, rrs.Column2});

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ASP.NET Core correct usage of ConfigureAwait with async/await

Lately we had a discussion on when to use ConfigureAwait(true) or ConfigureAwait(false) in ASP.NET Core 2. In the end most of the team, including me, had a faulty assumption on how to do this in ASP.NET Core. In this case ASP.NET Core is different from ASP.NET. Good to know if you have to decide on what to use in ASP.NET core.

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Cross process Application Insights with Multi-Role Application Map

Use Multi-Role Application Map to monitor cross process dependencies

When using Application Insights to monitor your Microservices environment, it would be nice to track calls over process boundaries. Application Insights has a preview for Multi-Role Application Maps. This enables you to visualize the dependencies over multiple processes and name the different processes. In this blog posts I will explain how to enable Multi Role Application Maps preview, give you different process names and add dependency tracking into your application. Continue reading “Cross process Application Insights with Multi-Role Application Map”

Implement Pessimistic Concurrency in Entity Framework Core

ConcurrencyIn a scenario where we were using SQL server as a queue, before publishing events to external queues, we wanted the data to be processed only once and in order, even with multiple processors for failover. When reading from the table we wanted to lock the records and block other processors from reading those records, while being processed. This is called Pessimistic Concurrency, unfortunately Entity Framework Core does not support this out of the box. To realize Pessimistic Concurrency you need to write your own SQL queries directly on the database (The solution is database type bound, in this case Microsoft SQL server). This blog post will show how it can be accomplished.
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Get your web application errors into Slack

Get your devops going by integrating your application into your team communication tooling.

bugbotTo get more out of Slack and your team, you can integrate Slack with your application. Integrating with slack is done with webhooks. In this sample I use a Incoming Webhook to post the messages from the application to slack. By adding a GlobalExceptionFilter to you .Net Core web application, you can get all exceptions that are not handled in your web application.
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