S6667 — Logging in a catch clause should pass the caught exception as a parameter.

This rule raises an issue on logging calls inside a catch clause that does not pass the raised Exception.

Why is this an issue?

A log entry should contain all the relevant information about the current execution context. The Exception raised in a catch block not only provides the message but also:

• the exception type
• the stack trace
• any inner exceptions
• and more about the cause of the error.

Logging methods provide overloads that accept an Exception as a parameter and logging providers persist the Exception in a structured way to facilitate the tracking of system failures. Therefore Exceptions should be passed to the logger.

The rule covers the following logging frameworks:

• Nuget package - Castle.Core
• Nuget package - Common.Core
• Nuget package - log4net
• Nuget package - NLog
• Nuget package - Microsoft.Extensions.Logging

How to fix it

Code examples

Noncompliant code example

public bool Save()
{
    try
    {
        DoSave();
        return true;
    }
    catch(IOException)
    {
        logger.LogError("Saving failed.");             // Noncompliant: No specifics about the error are logged
        return false;
    }
}

Compliant solution

public bool Save()
{
    try
    {
        DoSave();
        return true;
    }
    catch(IOException exception)
    {
        logger.LogError(exception, "Saving failed.");  // Compliant: Exception details are logged
        return false;
    }
}

Resources

Documentation

• Microsoft Learn - Log exceptions
• Microsoft Learn - LoggerExtensions Class
• Microsoft Learn - Logging providers
• Microsoft Learn - The try-catch statement
• Serilog - Example application
• Serilog Analyzer - Serilog001: Exception Usage