How do I fix: 🛑 Root Causes of the Error?

The problem arises when you are using Distinct() on a collection that contains duplicate elements. This is because Distinct() only returns unique elements, so if there are duplicates in your collection, they will be ignored.

How do I fix: Method 2: Use Include() with Distinct()?

Step 1: Use the Select() method to project your elements into a new collection, and then use the Distinct() method along with Include() to remove duplicates.

Coding⏱️ 2 min read📅 2026-05-31

How to Fix: Distinct not working with LINQ to Objects

Q: Best Solutions to Fix ItMethod 1: Remove Duplicates Before Using Distinct()?

Step 1: Use the ToList() method to convert your collection into a list, and then use the Distinct() method to remove duplicates.

The Distinct method is not working as expected with LINQ to Objects because it requires a unique identifier for each object in the list.

Quick Answer: Use a custom key or property that uniquely identifies each object, such as an ID field, or use a different approach like grouping and then selecting distinct groups.

📋 Table of Contents

🛑 Root Causes of the Error
✅ Best Solutions to Fix It
🎯 Final Words

Distinct not working with LINQ to Objects: A common issue in C# programming. In this article, we will explore the root causes of this error and provide best solutions to fix it.

🛑 Root Causes of the Error

The problem arises when you are using Distinct() on a collection that contains duplicate elements. This is because Distinct() only returns unique elements, so if there are duplicates in your collection, they will be ignored.

✅ Best Solutions to Fix It

Method 1: Remove Duplicates Before Using Distinct()

Step 1: Use the ToList() method to convert your collection into a list, and then use the Distinct() method to remove duplicates.

Method 2: Use Include() with Distinct()

Step 1: Use the Select() method to project your elements into a new collection, and then use the Distinct() method along with Include() to remove duplicates.

🎯 Final Words

In conclusion, using Distinct() on a collection that contains duplicate elements can lead to unexpected results. By removing duplicates before using Distinct(), or by using Include() with Distinct(), you can ensure that your LINQ queries return the expected results.

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