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CA2023: Invalid braces in message template

Property Value
Rule ID CA2023
Title Invalid braces in message template
Category Reliability
Fix is breaking or non-breaking Non-breaking
Enabled by default in .NET 10 As warning

Cause

The braces present in the message template are invalid. Ensure any braces in the message template are valid opening/closing braces, or are escaped.

Rule description

Logging message templates use curly braces { and } to denote named placeholders for values. Invalid brace usage in message templates can result in runtime exceptions or unexpected logging behavior. This rule detects:

  • Unmatched opening or closing braces.
  • Nested braces that aren't properly escaped.
  • Other malformed brace patterns.

How to fix violations

To fix a violation of this rule:

  • Ensure all opening braces { have a corresponding closing brace }.
  • Escape literal braces by doubling them: {{ for { and }} for }.
  • Fix any nested or malformed brace patterns.

Example

The following code snippet shows violations of CA2023:

using Microsoft.Extensions.Logging;

class Example
{
    private readonly ILogger _logger;

    public Example(ILogger<Example> logger)
    {
        _logger = logger;
    }

    public void LogData(string name, int value)
    {
        // Violation: unmatched opening brace.
        _logger.LogInformation("Processing {Name with value {Value}", name, value);

        // Violation: unmatched closing brace.
        _logger.LogInformation("Processing Name} with value {Value}", name, value);
    }
}

Imports Microsoft.Extensions.Logging

Class Example
    Private ReadOnly _logger As ILogger

    Public Sub New(logger As ILogger(Of Example))
        _logger = logger
    End Sub

    Public Sub LogData(name As String, value As Integer)
        ' Violation: unmatched opening brace.
        _logger.LogInformation("Processing {Name with value {Value}", name, value)

        ' Violation: unmatched closing brace.
        _logger.LogInformation("Processing Name} with value {Value}", name, value)
    End Sub
End Class

The following code snippet fixes the violations:

using Microsoft.Extensions.Logging;

class Example
{
    private readonly ILogger _logger;

    public Example(ILogger<Example> logger)
    {
        _logger = logger;
    }

    public void LogData(string name, int value)
    {
        // Fixed: proper braces.
        _logger.LogInformation("Processing {Name} with value {Value}", name, value);

        // Fixed: escaped literal braces.
        _logger.LogInformation("Processing {{Name}} with value {Value}", name, value);
    }
}

Imports Microsoft.Extensions.Logging

Class Example
    Private ReadOnly _logger As ILogger

    Public Sub New(logger As ILogger(Of Example))
        _logger = logger
    End Sub

    Public Sub LogData(name As String, value As Integer)
        ' Fixed: proper braces.
        _logger.LogInformation("Processing {Name} with value {Value}", name, value)

        ' Fixed: escaped literal braces.
        _logger.LogInformation("Processing {{Name}} with value {Value}", name, value)
    End Sub
End Class

When to suppress warnings

Don't suppress a warning from this rule. Invalid braces in message templates can cause runtime exceptions or incorrect log output.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA2023
// The code that's violating the rule is on this line.
#pragma warning restore CA2023

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.CA2023.severity = none

For more information, see How to suppress code analysis warnings.

See also

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