System.IO.FileNotFoundException: 'Could not load file or assembly 'Serlolg.Sinks.Console, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.'

[dca00]

Serilog packages are installed in my project:

They create these dependencies, console being one of them:

Configuration in appsettings.json:

  "SeriLog": {
    "Using": [ "Serilog.Sinks.Console", "Serilog.Sinks.File" ],
    "MinimumLevel": {
      "Default": "Debug",
      "Override": {
      }
    },
    "WriteTo": [
      {
        "Name": "Console",
        "Args": {
          "theme": "Serilog.Sinks.SystemConsole.Themes.AnsiConsoleTheme::Code, Serlolg.Sinks.Console",
          "outputTemplate": "[{Timestamp:HH:mm:ss} {SourceContext} {Level}] {Message}{NewLine}{Exception}",
        }
      },
      {
        "Name": "File",
        "Args": {
          "path": "C:/1/project.log",
          "rollingInterval": "Day",
          "outputTemplate": "[{Timestamp:HH:mm:ss} {SourceContext} {Level}] {Message}{NewLine}{Exception}",
          "formatter": {
            "type": "Serilog.Formatting.Compact.CompactJsonFormatter, Serilog.Formatting.Compact"
          }
        }
      }
    ],
    "Enrich": [
      "FromLogContext",
      "WithMachineName",
      "WithThreadId",
      "WithExceptionDetails"
    ],

When this application creates its logger:

var logger = new LoggerConfiguration().ReadFrom.Configuration(cfg).CreateLogger();

this error is thrown:

System.IO.FileNotFoundException: 'Could not load file or assembly 'Serlolg.Sinks.Console, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.'

Technically, it is true: there is no such file:

I uninstalled and reinstalled Serilog.Sinks.Console but the error is still there.

I saw a similar issue #407 closed, but I cannot follow the same pattern as my organization blocks stack exchange, and I won't be able to either create a question there or see any answers, so please let this stay here.

[nblumhardt]

If the application code doesn't reference the types in the package, it can end up trimmed out/not included in the output folder. Configuring the sink in code, or using this kind of pattern should sort it out:

var configurationAssemblies = new[]
{
    typeof(ConsoleLoggerConfigurationExtensions).Assembly,
    typeof(FileLoggerConfigurationExtensions).Assembly,
};
var options = new ConfigurationReaderOptions(configurationAssemblies);
var logger = new LoggerConfiguration()
    .ReadFrom.Configuration(configuration, options)
    .CreateLogger();

From https://github.com/serilog/serilog-settings-configuration?tab=readme-ov-file#using-section-and-auto-discovery-of-configuration-assemblies

[dca00]

The DLL does exist in the output folder:

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----         5/18/2025   5:22 PM         163328 Serilog.dll
-a----         12/8/2024   7:31 PM          35840 Serilog.Extensions.Hosting.dll
-a----         3/25/2025   1:14 AM          27648 Serilog.Extensions.Logging.dll
-a----         12/8/2024   7:16 PM          70144 Serilog.Settings.Configuration.dll
-a----          6/9/2024   6:13 PM          38400 Serilog.Sinks.Console.dll
-a----         6/14/2024   4:09 AM          10240 Serilog.Sinks.EventLog.dll
-a----         4/27/2025   8:38 PM          36864 Serilog.Sinks.File.dll

File sink is also not directly referenced from the code, but it is not throwing errors.

[0xced]

Have you tried @nblumhardt's suggestion to use ConfigurationReaderOptions with explicit references to the sink assemblies?

[dca00]

Hardcoding of sinks defeats the purpose of using Serilog. It won't be attempted.

[nblumhardt]

Knowing whether the explicit assembly loader approach works will narrow down where your problem is. It's most likely a tooling thing - something about how your project is built/packaged/run that makes the console sink behave differently from the file sink, so there isn't much for us to go on, otherwise.