Trace.Fail Method (String)


Emits the specified error message.

Namespace:   System.Diagnostics
Assembly:  System (in System.dll)

Public Shared Sub Fail (
	message As String


Type: System.String

A message to emit.

The default behavior for the default trace listener is to output the message parameter to a message box when the application runs in user-interface mode, and to the TraceListener instances in the Listeners collection.


The display of the message box is dependent on the presence of the DefaultTraceListener. If the DefaultTraceListener is not in the Listeners collection, the message box is not displayed. The DefaultTraceListener can be removed by the <clear> Element for <listeners> for <trace>, the <remove> Element for <listeners> for <trace>, or by calling the Clear method on the Listeners property (System.Diagnostics.Trace.Listeners.Clear()).

You can customize this behavior by adding a TraceListener to, or by removing one from, the Listeners collection.

The following example uses the Fail method to print a message during exception handling.

    Trace.Fail("Unknown Option " + option1 + ", using the default.")
End Try

You can also use the Fail method in a switch statement.

Select Case option1
    Case OptionConsts.First
        result = 1.0

    ' Insert additional cases.
    Case Else
        Trace.Fail(("Unknown Option " & option1))
        result = 1.0
End Select

.NET Framework
Available since 1.1
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