DEV Community: Yass- Cloud and AI Explorer

Can You Pass This .NET 11 Challenge? 3 Tricky EF Core 11 & ASP.NET Core 11 Scenarios (20-Question Quiz)

Yass- Cloud and AI Explorer — Mon, 26 Oct 2026 20:49:33 +0000

Following the great discussions on our recent guide covering What's New in EF Core 11 and ASP.NET Core 11, it's clear that while .NET 11 brings fantastic performance gains, its subtle breaking changes will catch many teams off guard in production.

To help developers audit their code before the November 2026 GA release, I created a full 20-Question Interactive Practice Test & Cheat Sheet on Iwalen.

Here are 3 tricky real-world scenarios from the test. Can you spot the bug or the right architectural fix? Drop your answers in the comments before checking the key! 👇

Challenge 1: The Disappearing Vectors in SQL Server 2025

Your RAG service re-ranks search results in C# after a database lookup. Right after upgrading to EF Core 11, the re-ranker throws an exception because doc.Embedding is null:

public class Document
{
    public int Id { get; set; }
    public required string Title { get; set; }

    [Column(TypeName = "vector(1536)")]
    public SqlVector<float> Embedding { get; set; }
}

var doc = await db.Documents.FirstAsync(d => d.Id == id);
var score = Reranker.Score(doc.Embedding, queryVector); // doc.Embedding is NULL in EF Core 11!

What is the fix?

A) Call .Include(d => d.Embedding) to include the vector column.
B) EF Core 11 omits SqlVector<T> columns from default entity SELECT statements; project the column explicitly via .Select(d => new { d.Id, d.Embedding }).
C) Change the property type to SqlVector<float>? because EF Core 11 only skips non-nullable vectors.
D) Await a lazy-loading proxy call because vectors are now lazy-loaded on property access.

Challenge 2: The Staging Authentication Crash

After upgrading an order service to EF Core 11, all integration tests pass locally against a Docker container with password auth. But in Azure staging, startup crashes immediately with this connection string:

Server=tcp:contoso-sql.database.windows.net;Database=Orders;Authentication=Active Directory Managed Identity;

No C# code changed during the upgrade. What is missing?

A) Managed Identity was removed from SqlClient 7.0; you must migrate to SQL authentication.
B) You must set UseCompatibilityLevel(150) in UseSqlServer(...) because level 160 breaks Entra ID tokens.
C) You must install Microsoft.Data.SqlClient.Extensions.Azure, because SqlClient 7.0 unbundled Entra ID dependencies from the core package.
D) Switch to Authentication=Active Directory Password, which remains in core SqlClient 7.0.

Challenge 3: The Cross-Assembly Validation Trap

You split your solution into a host project (Contoso.Api.dll) and a class library containing your Minimal API route groups (Contoso.Orders.Endpoints.dll):

// Host project Program.cs:
builder.Services.AddValidation();
app.MapOrderEndpoints();

// In Contoso.Orders.Endpoints.dll:
public static class OrderEndpoints
{
    public static void MapOrderEndpoints(this IEndpointRouteBuilder app) =>
        app.MapPost("/orders", (CreateOrderRequest req) => TypedResults.Ok(req));
}

public sealed class CreateOrderRequest
{
    [Required, Range(1, 100)] public int? Quantity { get; set; }
}

When a client sends { "quantity": 500 }, the endpoint returns 200 OK instead of 400 Bad Request. Why?

A) The validation source generator only scans types in the assembly where AddValidation() is called; you must call services.AddValidation() inside the endpoints assembly.
B) DataAnnotations in class libraries require registering builder.Services.AddControllers().
C) You must add [assembly: ValidatableType] inside the host Program.cs.
D) Minimal API validation is disabled in Production by default.

Ready to Test Yourself on All 20 Scenarios?

The full test covers 17 additional scenarios including:

Complex types on TPT/TPC hierarchies with .ToJson() & lambda chained indexing
Cosmos DB unmapped JSON data loss & synchronous I/O removal
SQL Server compatibility level 160 (LEAST/GREATEST) and 170 (JSON_CONTAINS)
Stripping no-op SQL CASTs and FullJoin LINQ queries
OpenAPI 3.2 default, binary response schemas (FileContentResult), and anyOf responses
Replacing the deleted ConcurrencyLimiter middleware
Built-in OpenTelemetry HTTP server span tags
Blazor DisplayName component precedence & QuickGrid URL-based pagination/sorting
Static SSR header-based CSRF protection (Sec-Fetch-Site) vs token middleware

Take the complete test, get an instant score breakdown, and inspect detailed architectural explanations for every option:

👉 Take the Free 20-Question .NET 11 Practice Test on Iwalen

EF Core 11 and ASP.NET Core 11 Changes That Will Bite You in Production (.NET 11)

Yass- Cloud and AI Explorer — Sat, 24 Oct 2026 16:54:23 +0000

With .NET 11 Release Candidate 2 out with a go-live license ahead of the November 2026 GA launch, many teams are preparing to bump their target frameworks from net10.0 to net11.0.

While C# 15 gets most of the spotlight (see our What's New in C# 15 Full Feature Guide), the runtime and framework updates inside EF Core 11 and ASP.NET Core 11 contain major new capabilities—along with several subtle breaking changes that can silently break production workloads.

Here is a quick breakdown of the biggest changes you need to know before upgrading.

👉 Read the complete EF Core 11 & ASP.NET Core 11 Guide (with Comparison Tables & 11-Step Upgrade Checklist) on Iwalen

1. `SqlVector<T>` Columns Now Return `null` by Default (EF Core 11)

The Problem in EF Core 10: Vector properties were loaded on every entity query just like strings or ints. Because embeddings carry hundreds or thousands of float values (e.g., 1,536 dimensions), routine entity queries dragged massive payloads across the wire even when you never read the vector in C#.

What Changed in EF Core 11: SqlVector<T> properties are now omitted from default entity SELECT statements, leaving the property null on materialized entities. (In the EF team's benchmarks, this made standard queries 9x faster locally and 22x faster against remote Azure SQL).

// Entity property (SQL Server 2025+):
[Column(TypeName = "vector(1536)")]
public SqlVector<float> Embedding { get; set; }

var docs = await db.Documents.OrderBy(d => d.Title).ToListAsync();
// EF Core 10: docs[0].Embedding contained the 1536-float vector
// EF Core 11: docs[0].Embedding is null (column omitted from SELECT)

// Need the vector values in C#? Project the column explicitly:
var vectors = await db.Documents
    .Select(d => new { d.Id, d.Embedding })
    .ToListAsync();

Gotcha: Because SqlVector<T> is often declared without ?, the compiler won't warn you. Grep your codebase for reads of .Embedding and convert them to explicit .Select(...) projections!

2. Complex Types Now Support JSON, TPT, TPC, and Direct Indexing (EF Core 11)

In EF Core 10, complex types and JSON columns couldn't be used on entities mapped with Table-per-Type (TPT) or Table-per-Concrete-Type (TPC) inheritance, and configuring nested properties required hopping through ComplexProperty(...).

In EF Core 11:

You can combine UseTptMappingStrategy() or UseTpcMappingStrategy() with complex types and .ToJson().
You can configure and index nested properties directly via lambda chaining:

// EF Core 11: chain member access directly inside Property()
modelBuilder.Entity<Customer>()
    .Property(c => c.Address.PostalCode)
    .HasMaxLength(12);

// Index a field inside a complex type directly:
modelBuilder.Entity<Customer>().HasIndex(c => c.Address.PostalCode);

// Relational + JSON: index a path inside a complex collection
modelBuilder.Entity<Order>().ComplexCollection(o => o.Items, b => b.ToJson());
modelBuilder.Entity<Order>().HasIndex("Items[].Sku");

3. `Microsoft.Data.SqlClient` 7.0 Splits Out Entra ID Authentication

EF Core 11 upgrades to Microsoft.Data.SqlClient 7.0, which removes the transitive Azure and Entra ID authentication dependencies (Azure.Identity, Microsoft.Identity.Client) from the core package.

If your production connection string uses ActiveDirectoryDefault, ActiveDirectoryManagedIdentity, or ActiveDirectoryServicePrincipal, your app will fail at runtime unless you explicitly install the new extension package:

<PackageReference Include="Microsoft.Data.SqlClient.Extensions.Azure" Version="7.0.0" />

(Note: Local development against a Docker SQL container with password auth won't catch this—test Managed Identity in staging!)

4. Cosmos DB Drops Unmapped JSON Properties on Save (High Impact!)

Because EF Core 11 switched the Cosmos DB provider from Newtonsoft.Json to System.Text.Json, the hidden __jObject shadow property is gone.

Previously, unmapped JSON properties in a Cosmos document were preserved in __jObject and written back on SaveChangesAsync(). In EF Core 11, unmapped properties are ignored on read and permanently lost when the entity is saved. Additionally, synchronous Cosmos I/O (ToList(), SaveChanges(), EnsureCreated()) now throws unconditionally with no opt-in switch.

5. End-to-End Async Validation & Localization in Minimal APIs (ASP.NET Core 11)

[ValidatableType] and [SkipValidation] have graduated from experimental status (no more ASP0029 warning suppressions!), and AddValidation() now supports asynchronous validators via AsyncValidationAttribute and IAsyncValidatableObject alongside automatic resource localization:

builder.Services.AddLocalization(); // Registers IStringLocalizerFactory
builder.Services.AddValidation();   // .NET 11 wires up localization automatically
builder.Services.AddScoped<IUserDirectory, SqlUserDirectory>();

var app = builder.Build();

app.MapPost("/signup", (SignupRequest request) =>
    TypedResults.Created($"/users/{request.Username}", request));

app.Run();

Cross-Assembly Trap: The validation source generator only discovers types in the assembly where AddValidation() is called. If your Minimal API endpoints live in a separate class library, expose an extension method in that assembly that calls services.AddValidation().

6. `ConcurrencyLimiter` Removed & OpenAPI Defaults to v3.2

Two major ASP.NET Core 11 shifts to audit before upgrading:

ConcurrencyLimiter Middleware Removed: UseConcurrencyLimiter(), AddQueuePolicy(), and AddStackPolicy() are gone in net11.0. Migrate to the built-in rate-limiting middleware (AddRateLimiter -> AddConcurrencyLimiter).
OpenAPI 3.2 by Default: OpenApiOptions.OpenApiVersion now defaults to OpenApiSpecVersion.OpenApi3_2 (powered by Microsoft.OpenApi 3.x), preserves multiple ProducesResponseType declarations per status code using anyOf, and supports binary file response schemas (FileContentResult).

7. Built-In OpenTelemetry HTTP Tags Out of the Box

In .NET 10, SuppressActivityOpenTelemetryData defaulted to true. In ASP.NET Core 11, it defaults to false, meaning the framework emits standard OpenTelemetry HTTP server-span tags (http.request.method, http.response.status_code, http.route, etc.) automatically without needing OpenTelemetry.Instrumentation.AspNetCore. Make sure to upgrade your instrumentation package if you use one so you don't get duplicate tags!

Read the Full Deep-Dive & 11-Step Upgrade Checklist

This post only scratches the surface. In the full technical guide, we cover:

Full comparison matrix: .NET 10 vs. .NET 11 across EF Core & ASP.NET Core
SQL Cleanups: Stripping no-op CASTs, split-query join pruning, and SQL Server compatibility level 160 / 170 (JSON_PATH_EXISTS, JSON_CONTAINS, FullJoin)
Blazor in .NET 11: <DisplayName>, QuickGrid URL pagination & OnRowClick, and automatic header-based CSRF protection
Step-by-step .NET 11 Production Upgrade Checklist

👉 Read the Full Guide: What's New in EF Core 11 and ASP.NET Core 11 (.NET 11)

How to Prepare for Microsoft Exam AI-103: 2026 Blueprint & Free 180-Question Practice Hub

Yass- Cloud and AI Explorer — Sun, 11 Oct 2026 21:25:40 +0000

Microsoft's AI-102 exam is officially retired, and the new active certification is Exam AI-103: Developing AI Apps and Agents on Azure (earning you the Microsoft Certified: Azure AI Apps and Agents Developer Associate credential).

If you are studying from legacy AI-102 guides or generic cloud courses, you're preparing for outdated tech. AI-103 is fundamentally re-architected around:

Microsoft Foundry platform & unified SDK
Autonomous AI Agents & Semantic Kernel orchestration
Production RAG pipelines with Document Intelligence v4.0 GA & Content Understanding
Responsible AI evaluation frameworks (groundedness, coherence, safety)

To help developers prepare without hitting paywalls, I built a comprehensive Complete AI-103 Study Guide & 180-Question Practice Hub.

The AI-103 Exam Blueprint Breakdown

The exam consists of 40–60 questions, has a 120-minute limit, and requires a passing score of 700/1000. Here is where the actual points are distributed:

Domain 1: Plan and prepare to develop AI apps and agents (~15%) — Foundry Hub vs Project structure, RBAC, Managed VNet, and Key Vault integration.
Domain 2: Develop Generative AI solutions with Foundry (~30%) — Azure OpenAI deployments, prompt caching, PTU vs PAYG, and content filtering.
Domain 3: Develop AI agents and agentic workflows (~25%) — Azure AI Agent Service, Semantic Kernel plugins, and multi-agent patterns (Sequential, Concurrent, Magentic).
Domain 4: Document intelligence and RAG pipelines (~20%) — Document Intelligence v4.0 models, Azure AI Search hybrid search, semantic ranker, and knowledge stores.
Domain 5: Responsible AI, evaluation, and monitoring (~10%) — Groundedness, coherence, fluency metrics, and Prompt Shields.

Top Exam Traps to Watch Out For

Content Understanding vs. Document Intelligence v4.0: Document Intelligence is document-centric OCR and layout analysis (now with Markdown output mode). Content Understanding in Microsoft Foundry is the multimodal tool specifically designed for RAG grounding with bounding-box coordinates.
Semantic Ranker vs. Vector Search: Vector search uses embedding similarity, whereas Semantic Ranker is a cross-encoder that re-scores top candidates using deep language understanding. Hybrid search (BM25 + vector) combined with Semantic Ranker is Microsoft's gold standard for mixed queries.
Agent State Management: Stateless single-turn agents differ from multi-turn agents on Azure AI Agent Service, where thread state is persisted server-side.

Full 9-Part Practice Curriculum (180 Questions)

Instead of passive reading, you can test your knowledge across 9 dedicated scenario modules (20 questions each) with deep architectural explanations for every option:

👉 You can access the complete master study guide, 4-week preparation roadmap, and all interactive test modules directly on Iwalen.com.

Happy studying, and best of luck on your certification journey!

DEV Community: Yass- Cloud and AI Explorer

Can You Pass This .NET 11 Challenge? 3 Tricky EF Core 11 & ASP.NET Core 11 Scenarios (20-Question Quiz)

Challenge 1: The Disappearing Vectors in SQL Server 2025

Challenge 2: The Staging Authentication Crash

Challenge 3: The Cross-Assembly Validation Trap

Ready to Test Yourself on All 20 Scenarios?

More from our .NET 11 & C# 15 Series:

EF Core 11 and ASP.NET Core 11 Changes That Will Bite You in Production (.NET 11)

1. `SqlVector<T>` Columns Now Return `null` by Default (EF Core 11)

2. Complex Types Now Support JSON, TPT, TPC, and Direct Indexing (EF Core 11)

3. `Microsoft.Data.SqlClient` 7.0 Splits Out Entra ID Authentication

4. Cosmos DB Drops Unmapped JSON Properties on Save (High Impact!)

5. End-to-End Async Validation & Localization in Minimal APIs (ASP.NET Core 11)

6. `ConcurrencyLimiter` Removed & OpenAPI Defaults to v3.2

7. Built-In OpenTelemetry HTTP Tags Out of the Box

Read the Full Deep-Dive & 11-Step Upgrade Checklist

More from our .NET 11 & C# 15 Series:

How to Prepare for Microsoft Exam AI-103: 2026 Blueprint & Free 180-Question Practice Hub

The AI-103 Exam Blueprint Breakdown

Top Exam Traps to Watch Out For

Full 9-Part Practice Curriculum (180 Questions)

DEV Community: Yass- Cloud and AI Explorer

Can You Pass This .NET 11 Challenge? 3 Tricky EF Core 11 & ASP.NET Core 11 Scenarios (20-Question Quiz)

Challenge 1: The Disappearing Vectors in SQL Server 2025

Challenge 2: The Staging Authentication Crash

Challenge 3: The Cross-Assembly Validation Trap

Ready to Test Yourself on All 20 Scenarios?

More from our .NET 11 & C# 15 Series:

EF Core 11 and ASP.NET Core 11 Changes That Will Bite You in Production (.NET 11)

1. SqlVector<T> Columns Now Return null by Default (EF Core 11)

2. Complex Types Now Support JSON, TPT, TPC, and Direct Indexing (EF Core 11)

3. Microsoft.Data.SqlClient 7.0 Splits Out Entra ID Authentication

4. Cosmos DB Drops Unmapped JSON Properties on Save (High Impact!)

5. End-to-End Async Validation & Localization in Minimal APIs (ASP.NET Core 11)

6. ConcurrencyLimiter Removed & OpenAPI Defaults to v3.2

7. Built-In OpenTelemetry HTTP Tags Out of the Box

Read the Full Deep-Dive & 11-Step Upgrade Checklist

More from our .NET 11 & C# 15 Series:

How to Prepare for Microsoft Exam AI-103: 2026 Blueprint & Free 180-Question Practice Hub

The AI-103 Exam Blueprint Breakdown

Top Exam Traps to Watch Out For

Full 9-Part Practice Curriculum (180 Questions)

1. `SqlVector<T>` Columns Now Return `null` by Default (EF Core 11)

3. `Microsoft.Data.SqlClient` 7.0 Splits Out Entra ID Authentication

6. `ConcurrencyLimiter` Removed & OpenAPI Defaults to v3.2