Outlook VSTO Error : 'Attempted to read or write protected memory'

Question

Hello everyone. I am seeing an issue I've never seen before. Hopefully someone can help. I am using Outlook 2007 and have developed my add-in in VS2008. The exact error is :

"2/22/2013 1:17:14 PM - MYREMINDERS_BEFOREREMINDERSHOW ERROR: EXCEPTION TYPE
------------------------------------------------------------------------------------------------------------------------------------------------------
SYSTEM.ACCESSVIOLATIONEXCEPTION

MESSAGE
------------------------------------------------------------------------------------------------------------------------------------------------------
ATTEMPTED TO READ OR WRITE PROTECTED MEMORY. THIS IS OFTEN AN INDICATION THAT OTHER MEMORY IS CORRUPT.

STACK TRACE
------------------------------------------------------------------------------------------------------------------------------------------------------
   AT VARIANTCLEAR(TAGVARIANT* PVARG)
   AT SYSTEM.RUNTIME.INTEROPSERVICES.CUSTOMMARSHALERS.ENUMERATORVIEWOFENUMVARIANT.MOVENEXT()
   AT OUTLOOKADDIN2.THISADDIN.MYREMINDERS_BEFOREREMINDERSHOW(BOOLEAN& CANCEL)

2/22/2013 1:17:14 PM - MYREMINDERS_BEFOREREMINDERSHOW FINISH."

The sub TestOutOfProcess() works on Application_Startup(), but throws the above error in myReminders_BeforeReminderShow(). I don't get it.

Private WithEvents myReminders As Outlook.Reminders

'Works in here
Private Sub Application_Startup() Handles Application.Startup
        TestOutOfProcess()
End Sub

'Does not work in here
Private Sub myReminders_BeforeReminderShow(ByRef Cancel As Boolean) Handles myReminders.BeforeReminderShow
        AppendLog("myReminders_BeforeReminderShow Begin.", Const_LogToScreen, Const_LogToFile)

        Try
            TestOutOfProcess()
        Catch ex As Exception
            AppendLog("myReminders_BeforeReminderShow Error: " & MyErrorMessage(ex).ToString, Const_LogToScreen, Const_LogToFile)
        Finally
            ' cancel the reminder
            Cancel = True
        End Try
End Sub

Public Sub TestOutOfProcess()
        Dim objReminder As Outlook.Reminder
        Dim objReminders As Outlook.Reminders

        objReminders = Application.Reminders

        For Each objReminder In objReminders
            If objReminder.Caption = taskSubject Then
                MsgBox("This does not work sometimes.", MsgBoxStyle.Information, "Test")
            End If
        Next

End Sub

Thanks once again!

Answer 1

Where does your code intantiate myReminders?

--
Ken Slovak
[MVP-Outlook]
http://www.slovaktech.com
Author: Professional Programming Outlook 2007

"ILJester" <=?utf-8?B?SUxKZXN0ZXI=?=> wrote in message news:890353b7-a1c7-447a-961a-4d48af3209e3...

Hello everyone. I am seeing an issue I've never seen before. Hopefully someone can help. I am using Outlook 2007 and have developed my add-in in VS2008. The exact error is :

"2/22/2013 1:17:14 PM - MYREMINDERS_BEFOREREMINDERSHOW ERROR: EXCEPTION TYPE
------------------------------------------------------------------------------------------------------------------------------------------------------
SYSTEM.ACCESSVIOLATIONEXCEPTION

MESSAGE
------------------------------------------------------------------------------------------------------------------------------------------------------
ATTEMPTED TO READ OR WRITE PROTECTED MEMORY. THIS IS OFTEN AN INDICATION THAT OTHER MEMORY IS CORRUPT.

STACK TRACE
------------------------------------------------------------------------------------------------------------------------------------------------------
   AT VARIANTCLEAR(TAGVARIANT* PVARG)
   AT SYSTEM.RUNTIME.INTEROPSERVICES.CUSTOMMARSHALERS.ENUMERATORVIEWOFENUMVARIANT.MOVENEXT()
   AT OUTLOOKADDIN2.THISADDIN.MYREMINDERS_BEFOREREMINDERSHOW(BOOLEAN& CANCEL)

2/22/2013 1:17:14 PM - MYREMINDERS_BEFOREREMINDERSHOW FINISH."

The sub TestOutOfProcess() works on Application_Startup(), but throws the above error in myReminders_BeforeReminderShow(). I don't get it.

Private WithEvents myReminders As Outlook.Reminders

'Works in here
Private Sub Application_Startup() Handles Application.Startup
        TestOutOfProcess()
End Sub

'Does not work in here
Private Sub myReminders_BeforeReminderShow(ByRef Cancel As Boolean) Handles myReminders.BeforeReminderShow
        AppendLog("myReminders_BeforeReminderShow Begin.", Const_LogToScreen, Const_LogToFile)

        Try
            TestOutOfProcess()
        Catch ex As Exception
            AppendLog("myReminders_BeforeReminderShow Error: " & MyErrorMessage(ex).ToString, Const_LogToScreen, Const_LogToFile)
        Finally
            ' cancel the reminder
            Cancel = True
        End Try
End Sub

Public Sub TestOutOfProcess()
        Dim objReminder As Outlook.Reminder
        Dim objReminders As Outlook.Reminders

        objReminders = Application.Reminders

        For Each objReminder In objReminders
            If objReminder.Caption = taskSubject Then
                MsgBox("This does not work sometimes.", 
MsgBoxStyle.Information, "Test")
            End If
        Next

End Sub

Thanks once again!

---

Ken Slovak MVP - Outlook

Answer 2

If I understand you correctly... the :

Private WithEvents myReminders As Outlook.Reminders

is module level. And it is instantiated within the following sub. And that sub is originally called from Application_Startup():

Public Sub StartRemindingMe()

        Dim olApp As Outlook.Application
        Dim olNS As Outlook.NameSpace
        Dim tsk As Outlook.TaskItem
        Dim tasksFolder As Outlook.MAPIFolder
        Dim tasks As Outlook.Items
        Dim matchingTasks As Outlook.Items
        Dim i As Long
        Dim task As Outlook.TaskItem
        ' only start watching reminders when I say so
        olApp = New Outlook.Application
        myReminders = olApp.Reminders
        ' delete any existing tasks
        olNS = olApp.GetNamespace("MAPI")
        tasksFolder = olNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderTasks)
        tasks = tasksFolder.Items
        matchingTasks = tasks.Restrict("[Subject] = '" & taskSubject & "'")
        For i = matchingTasks.Count To 1 Step -1
            task = matchingTasks.Item(i)
            If task.Subject = taskSubject Then
                With task
                    .MarkComplete()
                    .Delete()
                End With
            End If
        Next i

        Dim today As System.DateTime

        today = System.DateTime.Now

        ' create initial task
        tsk = Application.CreateItem(Outlook.OlItemType.olTaskItem)
        With tsk
            .Subject = taskSubject
            .StartDate = today
            .ReminderSet = True
            .ReminderTime = today.AddMinutes(MINSBETWEENSCANS)
            .Save()
        End With
    End Sub

Thanks.

Answer 3

You didn't show that initialization in the code you showed for the startup handler.

 

Never create a new Outlook.Application object within an Outlook COM addin:

 

    olApp = New Outlook.Application

Use the Application object passed to you in the startup event handler.

--
Ken Slovak
[MVP-Outlook]
http://www.slovaktech.com
Author: Professional Programming Outlook 2007

"ILJester" <=?utf-8?B?SUxKZXN0ZXI=?=> wrote in message news:fb51b282-f73a-4a1a-960e-76708217e822...

If I understand you correctly... the :

Private WithEvents myReminders As Outlook.Reminders

is module level. And it is instantiated within the following sub. And that sub is originally called from Application_Startup():

Public Sub StartRemindingMe()

        Dim olApp As Outlook.Application
        Dim olNS As Outlook.NameSpace
        Dim tsk As Outlook.TaskItem
        Dim tasksFolder As Outlook.MAPIFolder
        Dim tasks As Outlook.Items
        Dim matchingTasks As Outlook.Items
        Dim i As Long
        Dim task As Outlook.TaskItem
        ' only start watching reminders when I say so
        olApp = New Outlook.Application
        myReminders = olApp.Reminders
        ' delete any existing tasks
        olNS = olApp.GetNamespace("MAPI")
        tasksFolder = olNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderTasks)
        tasks = tasksFolder.Items
        matchingTasks = tasks.Restrict("[Subject] = '" & taskSubject & "'")
        For i = matchingTasks.Count To 1 Step -1
            task = matchingTasks.Item(i)
            If task.Subject = taskSubject Then
                With task
                    .MarkComplete()
                    .Delete()
                End With
            End If
        Next i

        Dim today As System.DateTime

        today = System.DateTime.Now

        ' create initial task
        tsk = Application.CreateItem(Outlook.OlItemType.olTaskItem)
        With tsk
            .Subject = taskSubject
            .StartDate = today
            .ReminderSet = True
            .ReminderTime = today.AddMinutes(MINSBETWEENSCANS)
            .Save()
        End With
    End Sub

Thanks.

---

Ken Slovak MVP - Outlook

Answer 4

Thank you Ken. I understand and did not notice the creation of the seperate application object. But I am confused by what you mean as "Use the Application object passed to you in the startup event handler.". I do not see the Application object being passed to me from the startup event handler. My startup event handler is below :

Private Sub Application_Startup() Handles Application.Startup
        StartRemindingMe()
End Sub

Is this the right handler you are referring too? Or are you referring to the addin startup handler? Can you illustrate or elaborate please.

Thank you.

Answer 5

Public olApp As Outlook.Application = Nothing

Private Sub Application_Startup() Handles Application.Startup

    olApp = ThisAddin.Application

    StartRemindingMe()
End Sub

VSTO does provide a trusted instance of the Outlook.Application object for you. In the snippet above I'm setting a global Application object in the startup handler. That trusted Application object is what should be used to always derive all your Outlook objects.

--
Ken Slovak
[MVP-Outlook]
http://www.slovaktech.com
Author: Professional Programming Outlook 2007

"ILJester" <=?utf-8?B?SUxKZXN0ZXI=?=> wrote in message news:60ae6b1c-200c-417f-b3e6-ff23fa1154b3...

Thank you Ken. I understand and did not notice the creation of the seperate application object. But I am confused by what you mean as "Use the Application object passed to you in the startup event handler.". I do not see the Application object being passed to me from the startup event handler. My startup event handler is below :

Private Sub Application_Startup() Handles Application.Startup
        StartRemindingMe()
End Sub

Is this the right handler you are referring too? Or are you referring to the addin startup handler? Can you illustrate or elaborate please.

Thank you.

---

Ken Slovak MVP - Outlook

Answer 6

I understand now! Thank you. I actually moved this code to my addin startup event handler :

Private ThisOutlookInstance As Outlook.Application = Nothing

ThisAddIn_Startup(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Startup

Not sure how I got sidetracked with Application_StartUp(). In other words I had 2 startup handlers. The above is the right place for it right? I used the below instead. The Me keyword means the same thing as 'ThisAddin.Application' right? When I reference 'ThisAddIn.Application' it is not a shared member.

ThisOutlookInstance = Me.Application

Thank you Ken.

Answer 7

Private Sub ThisAddIn_Startup() Handles Me.Startup

is the correct startup handler. That's the one VSTO provides for you.

VSTO handles the Extensibility events OnConnection() and OnStartupComplete() and uses those events to initialize itself. It then provides you with the VSTO startup event handler, ThisAddIn_Startup().

Me.Application is OK. I'm sorry about the ThisAddIn.Application, that's what I get for writing it off the top of my head. The equivalent of Me.Application would be Globals.ThisAddIn.Application. I forgot the Globals part.

---

Ken Slovak MVP - Outlook

Answer 8

Thank you Ken. I appreciate all your help.