Returns or sets a specifying the name of the object or application that originally generated the error. Read/write.

Remarks

The Source specifies a string expression representing the object that generated the error; the is usually the object's name or programmatic ID. Use Source to provide information when your code is unable to handle an error generated in an accessed object. For example, if you access Microsoft Excel and it generates a 

Division by zero
error, Microsoft Excel sets Err.Number to its error code for that error and sets Source to Excel.Application.

When generating an error from code, Source is your application's programmatic ID. For , Source should contain a name having the form project.class. When an unexpected error occurs in your code, the Source property is automatically filled in. For errors in a , Source contains the name. For errors in a class module, Source contains a name with the project.class form.

Example

This example assigns the Programmatic ID of an Automation object created in Visual Basic to the variable 

MyObjectID
, and then assigns that to the Source property of the Err object when it generates an error with the Raise method. When handling errors, you should not use the Source property (or any Err properties other than Number) programmatically. The only valid use of properties other than Number is for displaying rich information to an end user in cases where you can't handle an error. The example assumes that 
App
and 
MyClass
are valid references. 
Dim MyClass, MyObjectID, MyHelpFile, MyHelpContext ' An object of type MyClass generates an error and fills all Err object ' properties, including Source, which receives MyObjectID, which is a ' combination of the Title property of the App object and the Name ' property of the MyClass object. MyObjectID = App.Title & "." & MyClass.Name Err.Raise Number := vbObjectError + 894, Source := MyObjectID, _ Description := "Was not able to complete your task", _ HelpFile := MyHelpFile, HelpContext := MyHelpContext