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Mistakes Developers Make

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

In today’s fast-moving digital world, ASP.NET Core has become one of the most preferred frameworks for building scalable, secure, and high-performance applications. But even highly experienced developers fall into certain traps that can negatively affect performance, security, and maintainability.

At Xaylon Labs, where we specialize in innovative app development and top-tier ASP.NET development services, we’ve observed that avoiding a few common mistakes can drastically improve product quality and development efficiency.

  1. Misconfiguring Dependency Injection
    • Registering services with incorrect lifetimes
    • Overusing Singletons unnecessarily
    • Injecting too many dependencies into controllers

    How to avoid it: Understand the difference between Scoped, Transient, and Singleton. Keep constructors lightweight and modular.

  2. Ignoring Asynchronous Programming

    Using blocking calls (.Result, .Wait()) slows down performance and reduces scalability.

    How to avoid it: Make the full pipeline async. Use async I/O operations wherever possible.

  3. Incorrect Configuration & Environment Setup

    Hardcoding configuration values or mixing environments causes deployment failures.

    How to avoid it: Use appsettings.json, appsettings.{Environment}.json, and environment variables. Store secrets in Azure Key Vault or Secret Manager.

  4. Poor Error Handling

    Not having global exception handling causes blind spots and potential security leakage.

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

  5. Misusing Middleware Order

    Middleware works in sequence — wrong ordering causes unexpected behavior.

    Correct order example:

    • UseRouting() before UseEndpoints()
    • Authentication before Authorization
  6. Blocking the Thread Pool

    Heavy CPU-bound operations block the request pipeline.

    How to avoid it: Move heavy workloads to background services like Hangfire, Azure WebJobs, or Hosted Services.

  7. Inefficient Database Queries

    Entity Framework mistakes commonly slow down apps.

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

    How to avoid it: Optimize EF queries, add indexes, profile SQL queries, and use caching.

  8. No Caching Strategy

    Lack of caching increases latency and database load.

    How to avoid it:

    • MemoryCache for single-server apps
    • Distributed Cache (Redis) for cloud + load-balanced apps
  9. Poor API Versioning

    Adding new endpoints without versioning breaks backward compatibility.

    How to avoid it: Use Microsoft’s API Versioning NuGet package and follow patterns like /api/v1/products.

  10. Weak Security Practices
    • No HTTPS enforcement
    • Missing validations
    • CSRF/XSS vulnerabilities
    • No authentication/authorization layer

    How to avoid it: Use Identity/OAuth/JWT, validate user input, enable CORS, and enforce HTTPS redirection.

Conclusion

ASP.NET Core is incredibly powerful — but only when used correctly. Avoiding these common mistakes leads to faster apps, fewer bugs, stronger security, and cleaner architecture.

At Xaylon Labs, our expert team specializes in building and optimizing world-class ASP.NET Core applications. If you're planning to upgrade, optimize, or build your next ASP.NET Core project — we’re here to help.