.NET Options Validation in Application Startup

This article explains how to validate options in .NET application startup using the Options pattern with Microsoft.Extensions.Options. It covers binding configuration sections to strongly-typed classes, using DataAnnotations for validation, and the importance of ValidateOnStart() to fail fast on misconfiguration. It also introduces .NET 8 attributes like [ValidateObjectMembers] and [ValidateEnumeratedItems] for recursive validation of nested objects and collections. The guide includes code examples for ASP.NET Core and other .NET hosts, helping developers catch configuration errors early rather than at runtime.