Error logging for ASP.NET Core

Structured logging with Microsoft.Extensions.Logging

Logging uncaught exceptions is one thing. What about all of the log statements that developers need to add today? With our integration with Microsoft.Extensions.Logging, you can log everything from verbose to fatal messages from ASP.NET Core.

Since messages logged through Microsoft.Extensions.Logging goes in the same error log as uncaught errors, existing rules and notifications just work.

The elmah.io integration for Microsoft.Extensions.Logging supports structured logging. If you ever tried scrolling through file-based log files, you know how important being able to separate and search by properties can be.

Breadcrumbs

When backend methods in ASP.NET Core fail, it can be a challenging task to figure out what happened. The cookies, server variables, and similar information logged by elmah.io do not always help to figure out what went wrong. Looking through multiple log statements to see what happened just before the error has been a common practice for years. Until now!

With Breadcrumbs on elmah.io, you can both manually log breadcrumbs in memory and have ASP.NET Core store messages logged through Microsoft.Extensions.Logging and use them as breadcrumbs. When an error is thrown, elmah.io automatically picks up all of the error details as well as the preceding breadcrumbs leading up to the error. This will make it a lot quicker to find, reproduce, and fix errors.

Let your AI agent read your ASP.NET Core errors

Connect Claude Code, Cursor, VS Code or Visual Studio to the elmah.io MCP server. Your agent can list new errors, read the stack trace and request details, check what changed after a deployment, and mark an error as fixed when you ask.

In Claude Code, add the server with one command:

claude mcp add --transport http --client-id claudecode elmahio https://mcp.elmah.io/mcp

The MCP server is included on every plan and is currently in beta. Set up the MCP server.

elmah.io vs. ElmahCore

Set up in a few lines

Install the NuGet package, add your API key and log ID, and call UseElmahIo. That is the whole setup.

dotnet add package Elmah.Io.AspNetCore

builder.Services.AddElmahIo(options =>
{
    options.ApiKey = "API_KEY";
    options.LogId = new Guid("LOG_ID");
});

// ...

app.UseElmahIo();

Call UseElmahIo after UseExceptionHandler and UseAuthentication, and before your endpoints. Your API key and log ID are shown on the install page when you sign up. Read the full setup guide.

How it looks

Here is what elmah.io logs for an unhandled exception:

• The request, with URL, status code, cookies, form values and server variables.
• The exception type and the stack trace.
• Breadcrumbs, the log messages that led up to the error.
• Messages from Microsoft.Extensions.Logging in the same log. Failing health checks show up as heartbeats, and deployment tracking shows which release broke what.

Frequently asked questions