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Visual Basic .NET / Errors & Resources

Custom Exception

Learn Custom Exception in Visual Basic .NET through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.

10 min read • Intermediate

Custom Exception is an atomic Visual Basic .NET topic inside Errors & Resources. This lesson focuses on how the Custom Exception construct is written, what it changes, and when it is the right tool.

Trace the example line by line. Identify the exact syntax for Custom Exception, the input state before it runs, and the resulting value, control flow, database state, hardware behavior, or runtime effect afterward. Neighboring lessons use different constructs rather than renamed copies of this one.

Topic-specific example

vbnet-06-03-custom-exception.vb
vbnet Try It Live 
Class QuotaException : Inherits Exception
    Public Sub New(message As String) : MyBase.New(message) : End Sub
End Class
Throw New QuotaException("quota exceeded")
Edge case / engineering note

For Custom Exception, test the boundary that belongs to this exact feature rather than a generic failure case. Check invalid or empty input, NULL/unknown state, numeric limits, transaction or exception behavior, synthesis/runtime constraints, ownership/permission rules, or backtracking/control-flow effects where they apply.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

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