Why My .NET Core App Keeps Breaking: 7 Fails Every Dev Knows 🤦‍

 I’ve been working with .NET Core for years now, and while it’s powerful, flexible, and one of my favorite frameworks — it also has plenty of facepalm moments 😅. Sometimes it’s our fault as developers, sometimes it’s just the framework being quirky.

Here are 7 of the funniest (and most painful) .NET Core fails that I (and many other devs) have run into. If you’ve been there too, you’ll laugh in pain with me 👇

1. Forgetting to Call UseRouting() 🚧

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllers();
});

🔴 Fail: You forget app.UseRouting(); before UseEndpoints().
Result? Your controllers never get hit. You stare at a 404 forever.
✅ Fix: Always call app.UseRouting(); in the right order.

2. Connection String Secrets… Pushed to GitHub 😱

"ConnectionStrings": {
  "DefaultConnection": "Server=myserver;Database=app;User Id=sa;Password=SuperSecret123;"
}

🔴 Fail: Hardcoding your connection string and accidentally pushing it to GitHub.
✅ Fix: Use Secrets Manager or Environment Variables.

3. Middleware Order Madness 🔄

app.UseAuthentication();
app.UseAuthorization();
app.UseRouting();

🔴 Fail: Wrong middleware order = login never works.
✅ Fix: Correct order is:

app.UseRouting();
app.UseAuthentication();
app.UseAuthorization();

4. The DbContext Explosion 💣

services.AddScoped<AppDbContext>();

🔴 Fail: Accidentally registering DbContext as a singleton.
Result: Race conditions, disposed contexts, or database locked errors.
✅ Fix: Always AddDbContext<AppDbContext>() which uses scoped by default.

5. Swagger Showing 1,000 Endpoints 🐙

• You forget to clean up old controllers…

• Suddenly Swagger looks like a jungle.

• Half of them throw 500 errors because they aren’t wired properly.

✅ Fix: Clean unused controllers, version your API, and disable what you don’t expose.

6. Startup.cs Turned Into Startup.god.cs 📜

• All services dumped into ConfigureServices.

• 1,000 lines of service registrations.

• Scrolling = arm workout.

✅ Fix: Use extension methods and modules to organize.

7. Forgot to Add app.UseHttpsRedirection(); 🔐

• App works locally.

• Deploy to production… “Why is my API insecure?!”

• Client complains browser says “Not Secure.”

✅ Fix: Always force HTTPS in production.

Conclusion 🎉

.NET Core is amazing, but like any framework, it has its quirks — and we devs sometimes make them worse with silly mistakes. Hopefully, these fails made you laugh and reminded you to avoid them in your next project.

💬 What’s the funniest .NET Core fail you’ve encountered? Drop it in the comments below 👇