> ## Documentation Index > Fetch the complete documentation index at: https://ancplua.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Diagnostics > ErrorOrX analyzer diagnostics reference The ErrorOrX generator and analyzer emit diagnostics to help catch issues at compile time. ## Endpoint Diagnostics ### Handler Structure | ID | Severity | Description | | ------ | -------- | ------------------------------------------------- | | EOE001 | Error | Invalid return type - must return `ErrorOr` | | EOE002 | Error | Handler must be static | | EOE017 | Error | Anonymous return type not supported | | EOE020 | Error | Inaccessible type (private/protected) in endpoint | | EOE021 | Error | Type parameter not supported in return type | ### Route Validation | ID | Severity | Description | | ------ | -------- | --------------------------------------------------------------------- | | EOE003 | Error | Route parameter not bound to method parameter | | EOE004 | Error | Duplicate route pattern detected | | EOE005 | Error | Invalid route pattern syntax | | EOE023 | Warning | Route constraint type mismatch (e.g., `{id:int}` with `string` param) | ### Parameter Binding | ID | Severity | Description | | ------ | -------- | ------------------------------------------------------- | | EOE006 | Error | Multiple body sources on single endpoint | | EOE009 | Warning | `[FromBody]` on GET/DELETE method | | EOE011 | Error | Invalid `[FromRoute]` type | | EOE012 | Error | Invalid `[FromQuery]` type | | EOE013 | Error | Invalid `[AsParameters]` type | | EOE014 | Error | `[AsParameters]` type has no accessible constructor | | EOE016 | Error | Invalid `[FromHeader]` type | | EOE018 | Error | Nested `[AsParameters]` not supported | | EOE019 | Error | Nullable `[AsParameters]` not supported | | EOE025 | Error | Ambiguous parameter binding (GET/DELETE + complex type) | ### AOT & Serialization | ID | Severity | Description | | ------ | -------- | --------------------------------------------------------------- | | EOE007 | Warning | Type not AOT-serializable | | EOE030 | Info | Too many result types for `Results<>` union (max 6) | | EOE032 | Warning | Unknown error factory method | | EOE033 | Error | Undocumented interface call | | EOE040 | Warning | Missing CamelCase JSON policy on user's `JsonSerializerContext` | | EOE041 | Error | Missing `JsonSerializerContext` for AOT with `[FromBody]` | ### Response Attributes | ID | Severity | Description | | ------ | -------- | ----------------------------------------- | | EOE010 | Warning | `[AcceptedResponse]` on GET/DELETE method | ## API Versioning Diagnostics | ID | Severity | Description | | ------ | -------- | -------------------------------------------------------------------- | | EOE050 | Warning | `[ApiVersionNeutral]` and `[MapToApiVersion]` are mutually exclusive | | EOE051 | Warning | `[MapToApiVersion]` references undeclared version | | EOE052 | Warning | `Asp.Versioning.Http` package not referenced | | EOE053 | Info | Endpoint missing versioning when others use it | | EOE054 | Error | Invalid API version format | | EOE055 | Warning | Duplicate route parameter binding | API versioning support requires the `Asp.Versioning.Http` package. See the [API Versioning guide](/erroror/api-versioning) for setup instructions. ## Common Fixes ### EOE001: Invalid Return Type ```csharp theme={null} // ❌ Wrong [Get("/todos")] public static List GetAll() => _db.GetAll(); // ✅ Correct [Get("/todos")] public static ErrorOr> GetAll() => _db.GetAll(); ``` ### EOE002: Handler Must Be Static ```csharp theme={null} // ❌ Wrong public class TodoEndpoints { [Get("/todos")] public ErrorOr> GetAll() => ... } // ✅ Correct public static class TodoEndpoints { [Get("/todos")] public static ErrorOr> GetAll() => ... } ``` ### EOE003: Route Parameter Not Bound ```csharp theme={null} // ❌ Wrong - 'id' in route but not in params [Get("/todos/{id}")] public static ErrorOr Get() => ... // ✅ Correct [Get("/todos/{id}")] public static ErrorOr Get(Guid id) => ... ``` ### EOE004: Duplicate Route ```csharp theme={null} // ❌ Wrong - same route pattern [Get("/todos/{id}")] public static ErrorOr GetById(Guid id) => ... [Get("/todos/{todoId}")] // EOE004: Duplicate of /todos/{id} public static ErrorOr GetByTodoId(Guid todoId) => ... ``` ### EOE025: Ambiguous Parameter Binding ```csharp theme={null} // ❌ Wrong - complex type on GET without explicit binding [Get("/todos")] public static ErrorOr> Search(SearchFilter filter) => ... // ✅ Option 1: Explicit FromQuery [Get("/todos")] public static ErrorOr> Search([FromQuery] SearchFilter filter) => ... // ✅ Option 2: AsParameters [Get("/todos")] public static ErrorOr> Search([AsParameters] SearchFilter filter) => ... // ✅ Option 3: FromBody (if intentional) [Get("/todos")] public static ErrorOr> Search([FromBody] SearchFilter filter) => ... ``` ### EOE040: Missing CamelCase Policy ```csharp theme={null} // ❌ Wrong - no naming policy [JsonSerializable(typeof(Todo))] internal partial class AppJsonContext : JsonSerializerContext { } // ✅ Correct [JsonSourceGenerationOptions( PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase, DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull)] [JsonSerializable(typeof(Todo))] internal partial class AppJsonContext : JsonSerializerContext { } ``` ### EOE050: Version-Neutral with Mappings ```csharp theme={null} // ❌ Wrong - conflicting attributes [ApiVersionNeutral] [MapToApiVersion("2.0")] [Get("/health")] public static ErrorOr Check() => ... // ✅ Correct - use one or the other [ApiVersionNeutral] [Get("/health")] public static ErrorOr Check() => ... ``` ### EOE051: Mapped Version Not Declared ```csharp theme={null} // ❌ Wrong - 2.0 not in declared versions [ApiVersion("1.0")] public static class UsersEndpoints { [MapToApiVersion("2.0")] // EOE051 [Get("/users")] public static ErrorOr> GetAll() => ... } // ✅ Correct - declare all versions [ApiVersion("1.0")] [ApiVersion("2.0")] public static class UsersEndpoints { ... } ``` ### EOE054: Invalid API Version Format ```csharp theme={null} // ❌ Wrong - invalid formats [ApiVersion("v1")] // No "v" prefix allowed [ApiVersion("1.0.0.0")] // Too many segments // ✅ Correct - valid formats [ApiVersion("1.0")] [ApiVersion("2")] [ApiVersion("1.0-beta")] ``` ### EOE041: Missing JsonSerializerContext for AOT ```csharp theme={null} // ❌ Error - [FromBody] without JsonSerializerContext for AOT [Post("/todos")] public static ErrorOr Create([FromBody] CreateTodoRequest req) => ... // ✅ Correct - register a JsonSerializerContext // 1. Create your context [JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)] [JsonSerializable(typeof(CreateTodoRequest))] [JsonSerializable(typeof(Todo))] [JsonSerializable(typeof(ProblemDetails))] internal partial class AppJsonContext : JsonSerializerContext { } // 2. Register in Program.cs builder.Services.AddErrorOrEndpoints() .UseJsonContext(); ``` ### EOE055: Duplicate Route Parameter Binding ```csharp theme={null} // ❌ Warning - duplicate binding to same route parameter [Get("/files/{id}")] public static ErrorOr Get( [FromRoute(Name = "id")] Guid fileId, // Used [FromRoute(Name = "id")] string category) // EOE055: Ignored { return new File(fileId, category); } // ✅ Correct - use unique route parameter names [Get("/files/{fileId}/{category}")] public static ErrorOr Get(Guid fileId, string category) => ... ```