Depending on the case, you could also offer extra options such as try another feature, reopen a connection, override file protection, free up some resources or even a big PANIC button This option is very handy if the same error keeps coming up repeatedly. It's not necessary to code an error handling routine in every procedure you write in Visual Basic. Dev centers Windows Office Visual Studio Microsoft Azure More... this contact form
Depending on the error, the description may or may not be useful. (Microsoft Access, for example, has the the infamous error message "There is no message for this error.") Source The Error message is: "run-time error '-2147417851' method of object failed". For the sake of completeness, I've added that –rpetrich Apr 16 '09 at 10:01 As I pointed out in another incarnation of this question: I see one big drawback Move your line of code from the previous section to the Try part: Try rt1.LoadFile("C:\test10.txt", RichTextBoxStreamType.PlainText) Catch ex As Exception End Try When you run your programme, VB will Try to
Try TestThrow() Catch e As FileNotFoundException MessageBox.Show("Error occurred: " & e.Message) ' Use e.InnerException to get to error ' that triggered this one. Otherwise the caller will carry on in ignorance that the routine hasn't worked and might cause worse problems. MessageBox.Show(e.InnerException.Message) End Try End Sub Private Sub TestThrow() Dim lngSize As Long Dim s As FileStream ' No matter what happens, throw back ' a File Not Found exception. Learning resources Microsoft Virtual Academy Channel 9 MSDN Magazine Community Forums Blogs Codeplex Support Self support Programs BizSpark (for startups) Microsoft Imagine (for students) United States (English) Newsletter Privacy & cookies
The Catch word means "Catch any errors here". Using the Exception Inheritance Hierarchy In the exception hierarchy shown in Figure 4, you can see that ArgumentNullException inherits from ArgumentException, which inherits from SystemException, which inherits from Exception. Yes No Additional feedback? 1500 characters remaining Submit Skip this Thank you! You're the best choice since not only is your software great but you also give the best service.
If you know the line, you're much better off. The CDate function in FuncA will generate error 13 (type mismatch) because CDate can't make a date from the input data. Finally, the Class_Terminate event of class modules cannot raise an error because this event can also occur when no other code is executing in the application. Any of these will do as the base class for your own exception.
If you plan to allow the application to run unattended or on a remote computer, you can't simply display an error message because there will be nobody there to see it You use VB's On Error statement to setup an error trap. But simple vb6 developers will face problem to follow this. Ken is co-author of several books including Access 97 Developer's Handbook with Paul Litwin and Mike Gilbert, Access 2000 Developer's Handbooks with Paul Litwin and Mike Gilbert, Access 2002 Developer's Handbooks
In Visual Basic .NET, this involves adding additional Catch blocks for each error you'd like to trap individually. http://www.vb6.us/tutorials/error-handling Previously, you were just catching any error that might be thrown: Catch ex As Exception But if you know a "file not found" error might be thrown, you can add that Most developers don't expect to write line numbers these days. On Error Resume Next ' Defer error trapping.
In the above example, you can't easily tell which of the statements failed. weblink Passing Error Information If you want to intercept different exceptions and raise them all back out to the caller as a single exception type, Throw makes it easy. Error handlers can be dedicated blocks of code enabled by using On Error Goto label or can be inline handlers enabled by using On Error Resume Next. Private Sub MultipleExceptions() Dim lngSize As Long Dim s As FileStream Try s = File.Open(txtFileName.Text, FileMode.Open) lngSize = s.Length s.Close() Catch e As ArgumentException MessageBox.Show( _ "You specified an invalid filename.
What does "M.C." in "M.C. Not surprisingly, the parameters of the Raise method are the same as the properties of the Err object: Number, Description, Source, HelpContext, and HelpFile. Your only recourse is to experiment, see what error numbers you can generate by triggering errors while testing, and trap those specific errors in your code. http://forumyaren.com/visual-basic/visual-basic-400-error.php The file system can change between the time the user selects a file and the time that the code runs.
Adding a Simple Try/Catch/End Try Block In order to gracefully handle runtime errors, add a Try/Catch/End Try block around any code that you want to protect. In addition, it provides a FileSize property, so your procedures' callers can determine the size of the file that triggered the exception. If everything goes well, then it skips the Catch part.
While the Description and other properties may contain useful information, only the Number property is a reliable indicator of the exact error that occurred. Description) End Sub what does this piece of code means ?? In order to support the raising of exceptions of derived exception types, a Throw statement is supported in the language. If you are running in a partial-trust context, the code might throw an exception due to insufficient privileges.
For more information, see How to: Insert IntelliSense Code Snippets. Most event procedures are also fired by Visual Basic when no other code is running so these are also at the top of the tree. For example, if you are designing a database application and encounter a corrupted database file, the error handling code could give the user the option of attempting to repair the damaged http://forumyaren.com/visual-basic/visual-basic-unexpected-error-336.php End This is not recommended, but you can use the End statement to immediately terminate your application.