Modding:Modder Guide/APIs/Logging

Creating SMAPI mods

---

• Get started
• Game fundamentals
• Test & troubleshoot
• Release
• API reference

  Basic SMAPI APIs:

  • Mod structure
  • Manifest
  • Events
  • Configuration
  • Load & edit content
  • Data
  • Input
  • Logging
  • Reflection
  • Multiplayer
  • Translation
  • Update checks
  • Utilities

  Advanced SMAPI APIs:

  • Content packs
  • Mod console commands
  • Mod integrations
  • Harmony patching

• Specific guides

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The monitor API, available through this.Monitor in your mod class, mainly lets you write messages to the console window and log file.

Logging

Overview

You can log messages by calling this.Monitor.Log with a string message and a log level. These messages will appear in the SMAPI console and log file.

For example, this code:

this.Monitor.Log("a trace message", LogLevel.Trace);
this.Monitor.Log("a debug message", LogLevel.Debug);
this.Monitor.Log("an info message", LogLevel.Info);
this.Monitor.Log("a warning message", LogLevel.Warn);
this.Monitor.Log("an error message", LogLevel.Error);

...will produce log entries with a timestamp, log level, mod name, and message:

[18:00:00 TRACE NameOfMod] a trace message
[18:00:00 DEBUG NameOfMod] a debug message
[18:00:00 INFO NameOfMod] an info message
[18:00:00 WARN NameOfMod] a warning message
[18:00:00 ERROR NameOfMod] an error message

The text won't appear in color in the log file, but will appear in color in SMAPI console window as the game runs.

Log levels

The log level is semantic, meaning that the level itself conveys information (a Trace message means something different from an Error message). You should use the log level that's closest to your message's purpose:

level	purpose
Trace	Tracing info intended for developers, usually low-level troubleshooting details that are useful when someone sends you their error log. Trace messages won't appear in the console window by default (unless you have the "SMAPI for developers" version), though they're always written to the log file.
Debug	Troubleshooting details that may be relevant to the player.
Info	Info relevant to the player. This should be used judiciously.
Warn	Potential problems that the player should be aware of. This should be used rarely.
Error	A message indicating something went wrong.
Alert	Important information to highlight for the player when player action is needed (e.g., new version available). This is mainly meant for SMAPI itself, and should almost never be used by mods.

Log once

The LogOnce method lets you log a message just like the above, but only once per game launch. For example, you can use it to show a compatibility warning for an API call:

this.Monitor.LogOnce("Some Mod Name used the deprecated X API.", LogLevel.Warn);

Verbose logging

You can have messages appear in the log (and console in the for developers version) only if SMAPI's verbose logging option is enabled. This is meant for diagnostic information that's sometimes needed to troubleshoot, but doesn't need to be logged in most cases.

There are two ways to use it:

// log a TRACE message if verbose logging is enabled
this.Monitor.VerboseLog("This will only appear if verbose logging is enabled.");

// check the verbose option
if (this.Monitor.IsVerbose)
   this.Monitor("This will only appear if verbose logging is enabled.", LogLevel.Trace);

Players can enable verbose logging by adding your mod ID to the VerboseLogging field in the smapi-internal/StardewModdingAPI.config.json file. For example, this enables it for SMAPI and Content Patcher:

"VerboseLogging": [ "SMAPI", "Pathoschild.ContentPatcher" ],

FAQs

Where is the log file created?

It's output to the game's ErrorLogs data folder. See smapi.io/log for help finding the log file, and you can also upload your log there to see what it looks like. The log file is always created (even if there are no errors) and it's written continuously (so you don't need to exit the game to see the log so far).