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Tag: errors

154 posts · Page 9 of 16

2026-07-20 errors csharp csharp-14

Fix: CS8618 "Non-nullable property must contain a non-null value when exiting constructor" in C#

CS8618 means a non-nullable field or property was not initialized by the time the constructor finished. Set it in the constructor, give it a default, mark it required, or make it nullable.

2026-07-20 errors mcp claude-code

Fix: MCP Server Throws "fetch is not defined" and EBADENGINE on Node.js Below 18

An MCP server on Node 16 warns EBADENGINE at install, then dies with 'fetch is not defined' on the first tool call. Upgrade to Node 18+ (20+ for the 2.x SDK) or polyfill the web globals.

2026-07-19 errors mcp claude-code

Fix: Claude Code misreads an MCP server's stderr startup message as an error

Claude Code logs every MCP server stderr line at [ERROR] and marks working servers as failed. If your tools still run, it is cosmetic. Here is how to confirm it and quiet the noise.

2026-07-18 errors flutter dart

Fix: ScaffoldMessenger.of() was called with a context that does not contain a Scaffold (Flutter)

This error means the BuildContext you passed is above the Scaffold or ScaffoldMessenger, not below it. Wrap the caller in a Builder, extract it into its own widget, or use a GlobalKey.

2026-07-18 errors dart flutter

Fix: type 'Null' is not a subtype of type 'X' in Dart

This runtime error means a null reached a cast expecting a non-nullable type, almost always from JSON. Make the field nullable, or supply a default before the cast runs.

2026-07-17 errors dotnet dotnet-11

Fix: "413 Request Entity Too Large" when uploading a file to an ASP.NET Core endpoint

Kestrel caps request bodies at 30,000,000 bytes by default and returns 413 when you exceed it. Raise MaxRequestBodySize globally, per endpoint, or in web.config behind IIS.

2026-07-17 errors mcp claude-code

Fix: all MCP servers fail to load after one malformed-JSON syntax error in the config

One trailing comma or unescaped Windows path in your MCP config makes every server vanish, not just the broken one. Validate the JSON, fix the five usual suspects, restart.

2026-07-17 errors csharp dotnet

Fix: System.InvalidOperationException: Headers are read-only, response has already started

You set a header, status code, or content type after the body was already flushed. Set all headers before the first write, or guard with HttpResponse.HasStarted and OnStarting.

2026-07-17 errors csharp dotnet

Fix: "The property could not be mapped, because it is not a supported primitive type or a valid entity type" in EF Core 11

EF Core hit a property it does not know how to store. Map it as a complex type, convert it with HasConversion, give it a key, or ignore it with [NotMapped].

2026-07-06 errors dotnet dotnet-11

Fix: "415 Unsupported Media Type" from a minimal API endpoint in ASP.NET Core 11

A minimal API returns 415 when the request Content-Type does not match what the endpoint binds. Send Content-Type: application/json for a body-bound type, or use [FromForm] for form and file uploads.