System.nullreferenceexception' occurred in...exe

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When I try save information into the database without picture, i get this error:System.NullReferenceException' occurred in ...exe

these are my codes:

VB

Dim bytes() As Byte = ms.ToArray
            Dim UploadImage As Bitmap = PictureBox.BackgroundImage
            Dim stream As New MemoryStream()
            PictureBox.BackgroundImage.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg)
            Dim picture() As Byte = stream.GetBuffer()
            stream.Close()


            Dim ds As DataSet = New DataSet()
            Dim str As String
            str = "insert into Staff_Information(EmpID,Fname,Oname,Lname,Date_hired,Branch,Department,Grade,Pictures) values (@EmpID,@Fname,@Oname,@Lname,@Date_hired,@Branch,@Department,@Grade,@Pictures)"
            cmd = New SqlCommand(str, con)

            con.Open()
            cmd.Parameters.AddWithValue("@EmpID", txtempID.Text)
            cmd.Parameters.AddWithValue("@Fname", txtfname.Text)
            cmd.Parameters.AddWithValue("@Oname", txtothername.Text)
            cmd.Parameters.AddWithValue("@Lname", txtlname.Text)
            cmd.Parameters.AddWithValue("@Date_hired", dtpempl.Value)
            cmd.Parameters.AddWithValue("@Branch", txtbranch.Text)
            cmd.Parameters.AddWithValue("@Department", txtdepartment.Text)
            cmd.Parameters.AddWithValue("@Grade", txtgrade.Text)
            cmd.Parameters.AddWithValue("@Pictures", picture)

            cmd.ExecuteNonQuery()
            MsgBox("Successful Saved")
            con.Close()
            cmd.Dispose()

What I have tried:

Tried

Try

Catch ex As Exception

'End Try

Option but nothing happens
Please i need help

Posted 10-Aug-17 5:52am

Antwi

Updated 10-Aug-17 6:30am

Kornfeld Eliyahu Peter

v2

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Comments

Kornfeld Eliyahu Peter 10-Aug-17 11:53am

Go and use your debugger to find out the line and the cause...

F-ES Sitecore 10-Aug-17 11:57am

This question is asked every day. Please learn to search for your error message and learn to use the debugger to see what the code *is* doing, not what you *think* it's doing.

Richard MacCutchan 10-Aug-17 12:22pm


cmd.ExecuteNonQuery()
MsgBox("Successful Saved")

Do not do this. You have no idea whether the ExecuteNonQuery() was successful or not because, like so many so-called developers, you do not bother to check the return status. You need to check everything in your code, do not assume that it does what you think.

Richard Deeming 10-Aug-17 14:54pm

To be fair, if the INSERT fails, the ExecuteNonQuery will throw an exception. If it finishes without throwing an exception, it's probably safe to assume that the insert succeeded.

If it was an UPDATE or a DELETE, then it would be necessary to check the return value. :)

Richard MacCutchan 11-Aug-17 3:44am

You should still check the return value.

Karthik_Mahalingam 11-Aug-17 1:08am

which line

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OriginalGriff · Answer 1 · 2017-08-10T06:30:00

This is one of the most common problems we get asked, and it's also the one we are least equipped to answer, but you are most equipped to answer yourself.

Let me just explain what the error means: You have tried to use a variable, property, or a method return value but it contains null - which means that there is no instance of a class in the variable.
It's a bit like a pocket: you have a pocket in your shirt, which you use to hold a pen. If you reach into the pocket and find there isn't a pen there, you can't sign your name on a piece of paper - and you will get very funny looks if you try! The empty pocket is giving you a null value (no pen here!) so you can't do anything that you would normally do once you retrieved your pen. Why is it empty? That's the question - it may be that you forgot to pick up your pen when you left the house this morning, or possibly you left the pen in the pocket of yesterdays shirt when you took it off last night.

We can't tell, because we weren't there, and even more importantly, we can't even see your shirt, much less what is in the pocket!

Back to computers, and you have done the same thing, somehow - and we can't see your code, much less run it and find out what contains null when it shouldn't.
But you can - and Visual Studio will help you here. Run your program in the debugger and when it fails, VS will show you the line it found the problem on. You can then start looking at the various parts of it to see what value is null and start looking back through your code to find out why. So put a breakpoint at the beginning of the method containing the error line, and run your program from the start again. This time, VS will stop before the error, and let you examine what is going on by stepping through the code looking at your values.

But we can't do that - we don't have your code, we don't know how to use it if we did have it, we don't have your data. So try it - and see how much information you can find out!