Setup

• Clone this repo
• Open Startup.cs and update this line with proper API_KEY and LOG_ID:

app.UseElmahIo("API_KEY", new Guid("LOG_ID"));

• Run the project

Testing elmah.io behavior 1

• Test 400 error: http://localhost:53276/?throw400=true
• Test 500 error: http://localhost:53276/?throw500=true

Notice that neither error is logged in elmah.io. This is strange as elmah.io should be able to inspect the response and notice that a 500 response is returned to the client in the second test.

Testing elmah.io behavior 2

Move registration of HandleExceptionMiddleware to before elmah.io in Startup:

app.UseMiddleware<HandleExceptionMiddleware>();
app.UseElmahIo("API_KEY", new Guid("LOG_ID"));

• Test 400 error: http://localhost:53276/?throw400=true
• Test 500 error: http://localhost:53276/?throw500=true

Notice that both errors are logged in elmah.io and both are reported as 500 errors. This makes sense as elmah.io handles the exceptions before HandleExceptionMiddleware gets a chance to change the response code.