Top 10 Mistakes Developers Make in ASP.NET Core — And How to Avoid Them

In today’s fast-moving digital world, ASP.NET Core is one of the most preferred frameworks for building scalable, high-performance applications. Whether you’re developing enterprise software or modern web apps, the framework offers flexibility, speed, and cross-platform capability. But even experienced developers fall into common traps that affect performance, security, and maintainability.

At Xaylon Labs, where we focus on innovative app development and top-tier ASP.NET development services, we’ve seen how avoiding simple mistakes can drastically improve product quality and development efficiency.

Below are the 10 most common mistakes developers make in ASP.NET Core — and how to avoid them.

1. Misconfiguring Dependency Injection

Dependency Injection (DI) is at the core of ASP.NET Core. But many developers:

• Register services with the wrong lifetime
• Overuse singletons
• Inject too many dependencies in controllers

How to avoid it:
Use DI wisely — understand the difference between scoped, transient, and singleton. Keep constructors light and modular.

2. Ignoring Asynchronous Programming

ASP.NET Core thrives on async/await. Developers who use blocking calls (.Result, .Wait()) slow down the system.

How to avoid it:
Make your entire pipeline async. Ensure all I/O operations use async methods.

3. Incorrect Configuration & Environment Setup

Many developers hardcode configuration values or mix environment settings, leading to deployment issues.

How to avoid it:
Use appsettings.json, appsettings.{Environment}.json, and environment variables properly. Never hardcode secrets — use Azure Key Vault or Secret Manager.

4. Poor Error Handling

Skipping global exception handling creates blind spots and security risks.

How to avoid it:
Implement a global exception middleware. Log all exceptions using Serilog, NLog, or Elastic Stack.

5. Not Leveraging Middleware Properly

Developers sometimes misuse or misplace middleware components, causing unexpected behavior.

How to avoid it:
Understand middleware order. For example:

• UseRouting() should come before UseEndpoints()
• Authentication must come before authorization

6. Blocking the Thread Pool

Overloading CPU-bound tasks can slow down or halt the app.

How to avoid it:
Move heavy tasks to background workers using:

• Hangfire
• Azure WebJobs
• Hosted Services

7. Inefficient Database Queries

Many developers combine Entity Framework with inefficient patterns, causing slow performance.

Common issues:

• Not using. AsNoTracking()
• N+1 query problems
• Missing indexes

How to avoid it:
Optimize EF queries. Profile SQL commands. Use caching and proper indexing.

8. Not Implementing Caching

A huge mistake is ignoring caching, which can significantly slow down high-traffic apps.

How to avoid it:
Utilize:

• MemoryCache for single-server apps
• Distributed Cache (like Redis) for cloud apps

This improves performance and reduces database load.

9. Poor API Versioning

Developers release new endpoints without versioning, causing issues with backward compatibility.

How to avoid it:
Implement API versioning using Microsoft’s API Versioning NuGet package.
 Use clear patterns such as:
 api/v1/products

10. Weak Security Practices

Common security mistakes include:

• Not using HTTPS
• Missing validation
• Leaving XSS/CSRF vulnerabilities
• No authentication/authorization layers

How to avoid it:
Use Identity, OAuth, or JWT. Always validate user inputs. Implement CORS and enforce HTTPS redirection.

Conclusion

ASP.NET Core is powerful — but only when used correctly. Avoiding these common mistakes can make your application faster, safer, and far more reliable.

At Xaylon Labs, our expert team specializes in app development and world-class ASP.NET development services. We help businesses build robust, scalable applications that deliver exceptional performance.

If you’re planning to upgrade, optimize, or build your next ASP.NET Core project, Xaylon Labs is here to assist.

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