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IsError Function

Returns a Boolean value indicating whether an expression is an exception type.

Public Function IsError(ByVal Expression As Object) As Boolean


  • Expression
    Required. Object expression.


IsError returns True if the expression represents an Object variable that derives from the Exception class in the System namespace.

An exception that derives from System.Exception can be caught with the Try...Catch...Finally statements.


The following example uses the IsError function to check if an expression represents a system exception.

Sub demonstrateIsError(ByVal firstArg As Integer)
    Dim returnVal As New Object 
    Dim badArg As String = "Bad argument value" 
    Dim errorCheck As Boolean 
    If firstArg > 10000 Then
        returnVal = New System.ArgumentOutOfRangeException(badArg)
    End If
    errorCheck = IsError(returnVal)
End Sub


Namespace: Microsoft.VisualBasic

Module: Information

Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

See Also


IsArray Function (Visual Basic)

IsDate Function (Visual Basic)

IsDBNull Function

IsNothing Function

IsNumeric Function (Visual Basic)

IsReference Function

Object Data Type

TypeName Function (Visual Basic)