If you work with C# and .NET long enough, you start noticing something.

The hardest part of software development isn't always building a complicated feature.

Sometimes it's a tiny problem that shouldn't take more than five minutes—but somehow takes an hour.

Why is my API using so much memory?

Why is this LINQ query suddenly slow?

Why isn't dependency injection resolving my service?

Why am I getting ObjectDisposedException?

Why isn't my async method behaving the way I expected?

Why is this code working locally but failing in production?

These are the kinds of problems .NET developers encounter repeatedly.

And that's exactly why I created 50 .NET Problems — Small Problems. Simple Solutions.

Get the 50 .NET Problems guide on Gumroad

The problem with learning .NET from tutorials

Most programming tutorials teach you how to build something.

You follow the steps:

Create a project.
Add some classes.
Configure dependency injection.
Create an API.
Connect a database.
Run the application.

Everything works.

But real-world development doesn't work like that.

Real applications have existing code, legacy decisions, performance problems, unexpected exceptions, configuration issues, concurrency problems, and production-specific behavior.

You aren't usually asking:

"How do I create an ASP.NET Core application?"

You're asking:

"Why is my existing ASP.NET Core application doing this?"

That's a very different problem.

Small .NET problems can consume a lot of time

Consider a few examples.

Your API is using too much memory

The application works perfectly.

Then memory usage keeps increasing.

You start wondering:

Is the garbage collector broken?
Is there a memory leak?
Am I holding references somewhere?
Is Entity Framework tracking too many objects?
Am I loading too much data?
Is a singleton holding application state?

The actual problem might be surprisingly simple.

Your LINQ query is slow

The LINQ code looks clean.

Something like:

var customers = customers
    .Where(x => x.IsActive)
    .OrderBy(x => x.Name)
    .ToList();

But the application is slow.

The important question isn't simply:

"How do I make LINQ faster?"

It's:

"Where is the work actually happening?"

Is the query executing in memory?

Is Entity Framework translating it to SQL?

Is the database missing an index?

Are you retrieving thousands of records unnecessarily?

A small misunderstanding can create a large performance problem.

Dependency injection suddenly fails

You see an exception similar to:

Unable to resolve service for type ...

The service exists.

The interface exists.

The constructor looks correct.

But the application won't start.

Again, the problem may be small—but finding the exact cause can take time.

That's what this guide is about

50 .NET Problems — Small Problems. Simple Solutions. is designed as a practical reference for developers who want quick, understandable solutions to common C# and .NET problems.

Instead of giving you a 500-page theory-heavy book, the idea is simple:

Problem → Explanation → Practical solution.

You can open the guide when you're stuck, find the problem that looks familiar, understand what's happening, and get back to coding.

What kinds of problems are covered?

The guide focuses on practical problems across areas such as:

C# fundamentals

Common issues involving:

Strings
Collections
Null handling
Exceptions
Type conversions
Object behavior
Common coding mistakes

LINQ

Problems involving:

Unexpected query execution
Performance
IEnumerable
IQueryable
Deferred execution
Filtering and projection

ASP.NET Core

Common problems involving:

Dependency injection
Middleware
Configuration
API behavior
Request handling
Authentication and authorization

Entity Framework Core

Problems involving:

Query performance
Tracking
Database calls
Loading related data
Unexpected SQL execution

Async and concurrency

Including problems around:

async / await
Task
Deadlocks
Blocking asynchronous code
ConfigureAwait
ValueTask

Performance

Practical issues involving:

Excessive allocations
Memory usage
Slow APIs
Inefficient queries
Unnecessary work

You don't need another programming book

There are already thousands of excellent books and courses about C# and .NET.

This guide isn't trying to replace them.

Instead, think of it as a developer's troubleshooting notebook.

You don't read a troubleshooting guide from beginning to end every time your application breaks.

You search for the problem you're experiencing.

That's the philosophy behind this product.

Who is this for?

This guide can be useful if you're:

A junior .NET developer

You are still learning how C# and .NET behave in real applications.

The practical examples can help you understand common mistakes faster.

A mid-level developer

You've been working with .NET for a few years and frequently encounter problems that aren't covered in basic tutorials.

This guide gives you a compact reference to keep nearby.

A senior developer

Even experienced developers occasionally forget the exact behavior of a framework feature or need a quick reminder before investigating a problem.

Small problems don't disappear when you become senior.

You just get better at solving them.

Preparing for .NET interviews

Many interview questions are based on real development problems.

Understanding why something happens is usually more valuable than memorizing definitions.

The goal isn't to memorize 50 solutions

This is important.

The value isn't simply knowing:

"Problem #17 has solution X."

The real goal is developing a troubleshooting mindset.

When something goes wrong, ask:

What exactly is happening?

Where is the work happening?

What assumption am I making?

Can I reproduce the problem?

What does the framework actually do here?

Can I reduce the problem to a smaller example?

Those questions are useful far beyond the 50 problems in this guide.

Small problems are worth solving well

Software development is often described in terms of big things:

Microservices
Cloud architecture
AI
Distributed systems
Kubernetes
Event-driven architecture
System design

Those subjects are important.

But your working day is also filled with much smaller problems.

A null reference.

A slow query.

A service that won't resolve.

A configuration value that is missing.

A task that isn't awaited.

An API returning unexpected data.

A collection containing duplicate values.

A performance issue caused by one seemingly harmless line of code.

These problems may be small individually.

But collectively, they can consume a significant amount of development time.

A practical reference you can keep nearby

That's why I built 50 .NET Problems — Small Problems. Simple Solutions.

It's designed to be something you can keep on your laptop, tablet, or e-reader and return to whenever you encounter a familiar .NET problem.

No complicated learning path.

No huge course.

No requirement to read hundreds of pages before getting value.

Just practical .NET problems and straightforward solutions.

Ready to solve some of those annoying .NET problems?

If you're a C#/.NET developer, you'll probably recognize several of these problems from your own projects.

Get the guide here:

👉 50 .NET Problems — Small Problems. Simple Solutions

Keep it as a practical reference for the next time your .NET application decides to behave unexpectedly.

Small problem. Simple solution. Less time debugging.

The .NET Engineer

50 .NET Problems Every Developer Eventually Faces — And the Simple Solutions