I’ve been using NLog for quite some time already, and it was a natural choice to use it in the ASP.NET Core projects as well. I’ve configured the logger using this tutorial and everything seemed to be working fine. Unfortunately, after some time we’ve noticed that for some reasons some of the errors are not logged. We’ve taken a deeper look at our code base and we’ve found couple logs being written as follows
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_logger.LogError(exception.HResult, exception, string.Empty); _logger.LogCritical(exception.HResult, exception, string.Empty); |
This piece of code works perfectly fine with ASP.NET Core console logger but it seems it doesn’t for NLog.
We double checked that with following piece of code
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[Route("api/[controller]")] public class ValuesController : Controller { private readonly ILogger<ValuesController> _logger; public ValuesController(ILogger<ValuesController> logger) { _logger = logger; } // GET api/values [HttpGet] public IEnumerable<string> Get() { var exception = new Exception(); _logger.LogTrace("Log trace"); _logger.LogDebug("Log debug"); _logger.LogInformation("Log information"); _logger.LogWarning("Log warning"); _logger.LogError(exception.HResult, exception, string.Empty); // this one will not be logged _logger.LogCritical(exception.HResult, exception, string.Empty); // this one will not be logged as well return new string[] {"value1", "value2"}; } } |
And as you can see in the picture below, no errors have been reported
Changing the error message to any message (even the one containing only white spaces)
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_logger.LogError(exception.HResult, exception, " "); _logger.LogCritical(exception.HResult, exception, " " ); |
fixed the problem.
That looks like a bug for me, so I will create a PR with the fix and see if that will make its way to the “master”
As usual, the source code for this post can be found on my GitHub
Have you created a pull request for this bug?
Yes, click. Once this is merged NLog.Web package will have to be updated as well – I’ve reported an issue for that as well click