access/mysql write conflict error

getting a little further. I have several previous versions of the app and they all exhibit the same problem. I have also learned that a number of datetime fields were added to the mysql backend. Checking that I find that there are a number of null datetime fields in the record, which I understand is a problem. So I'm leaning in this direction as my problem source. any comments appreciated.

Yes, I have a comment.  Please post the code in question, OK?

Ray below is the code behind the "save and close" button on the form. note that this not a new record and the error occurs on the first requery statement.

code start
Private Sub cmdEditApptTrSaveAndClose_Click()
On Error GoTo Err_cmdEditApptTrSaveAndClose_Click
Dim theIDPrep As Long
Dim theAppTrIDPrep As Long
Dim theIDSetUp As Long
Dim theAppTrIDSetUp As Long
Dim theAppTimeSlotPr As Long
Dim adjAppTimeSlot As String

Forms!frmAppt_PopUp_Edit_ApptTr.Requery
   
'****************************************************************************************************************************
    If IsNull([JobStatusText]) Then
        MsgBox "Please choose a valid appointment status", vbDefaultButton1, "Data Entry Warning"
        Exit Sub
    End If
'****************************************************************************************************************************
    If [JobStatusText] = "Scheduled" And IsNull([AppDate]) Then
        MsgBox "Please provide an appointment date", vbDefaultButton1, "Data Entry Warning"
        Me.AppDate.SetFocus
        Exit Sub
    End If
'****************************************************************************************************************************
    If IsNull([AppTimeSlot]) And Me.JobStatusText = "Scheduled" Then
        MsgBox "Please provide a time slot", vbCritical, "Data Entry Warning"
        Exit Sub
    End If
'****************************************************************************************************************************
    If IsNull([AppDuration]) And Me.JobStatusText = "Scheduled" Then
        MsgBox "Please provide an appointment duration", vbCritical, "Data Entry Warning"
        Me.AppDuration.SetFocus
        Exit Sub
    End If
'****************************************************************************************************************************
    If [JobConfStatus] = "Confirmed" And IsNull([JobConfName]) Then
        MsgBox "Please provide a confirmation name", vbDefaultButton1, "Data Entry Warning"
        DoCmd.GoToControl "JobConfName"
        Exit Sub
    End If
'****************************************************************************************************************************
    If Not IsNull([ReschedReason]) And IsNull([WhyNotScheduled]) Then
        MsgBox "Please provide a cancellation comment", vbDefaultButton1, "Data Entry Warning"
        DoCmd.GoToControl "WhyNotScheduled"
        Exit Sub
    End If
'****************************************************************************************************************************
    If [SentStatus] = "Sent" And IsNull([SentDate]) Then
        MsgBox "Please provide an inspection report sent date", vbDefaultButton1, "Data Entry Warning"
        DoCmd.GoToControl "SentDate"
        Exit Sub
    End If
'****************************************************************************************************************************
   
    If Me.AppNew = "New" And Me.JobStatusText = "Scheduled" And Left(Me.AppType, 8) = "Training" Then
   
        Dim theResp As Long
       
            theResp = MsgBox("Would you like to auto-add the set-up and prep appointments?", vbYesNo, "Training Appointment")
   
                If theResp = 6 Then

                    theIDPrep = DMax("[AppID]", "tblAppt") + 1
                    theAppTrIDPrep = DMax("[AppTrackingID]", "tblAppt_Tracking") + 1
                    theAppTimeSlotPr = DLookup("[AppTimeSlotPr]", "qryApptDur_PrNbr") - 2
                    adjAppTimeSlot = DLookup("[AppTimeSlot]", "temp_Appt_Tracking_AppTimeSlot", "[AppTimeSlotPr] = " & theAppTimeSlotPr)
               
                    Me.AppNew = Null
                   
                        Set theSet = CurrentDb.OpenRecordset("tblAppt")
                        theSet.AddNew
                        theSet![LocID] = Forms![frmLoc].[LocID]
                        theSet![AppType] = "Training Prep"
                        theSet![EnteredBy] = DLookup("[UserID]", "temp_Users")
                        theSet![EnteredDate] = Date
                        theSet![EnteredTime] = Time
                        theSet![AppID] = theIDPrep
                        theSet.Update
                        theSet.Close
                       
                    Dim WkDayApp As Date
                   
                        WkDayApp = Switch(Weekday(Me.AppDate) = 3, DateAdd("d", Me.AppDate, -4), Weekday(Me.AppDate) = 4, DateAdd("d", Me.AppDate, -5), Weekday(Me.AppDate) = 2 Or Weekday(Me.AppDate) = 5 Or Weekday(Me.AppDate) = 6, DateAdd("d", Me.AppDate, -3))
                       
                        Set theSet2 = CurrentDb.OpenRecordset("tblAppt_Tracking")
                        theSet2.AddNew
                        theSet2![AppID] = theIDPrep
                        theSet2![JobStatusText] = "Scheduled"
                        theSet2![AppDate] = WkDayApp
                        theSet2![InspectorName] = Me.[InspectorName]
                        theSet2![AppTimeSlot] = "7:30a"
                        theSet2![AppDuration] = "1.0 Hr"
                        theSet2![IRTruckTrlr] = 0
                        theSet2![IRElec] = 0
                        theSet2![IRGenInd] = 0
                        theSet2![IRStorage] = 0
                        theSet2![IRExcav] = 0
                        theSet2![IRMaint] = 0
                        theSet2![IRMatStorage] = 0
                        theSet2![IRHvyEquip] = 0
                        theSet2![IRProtEquip] = 0
                        theSet2![IRConfSpace] = 0
                        theSet2![IRScaffolds] = 0
                        theSet2![IRLadders] = 0
                        theSet2![IRWkZone] = 0
                        theSet2![IRMisc] = 0
                        theSet2![IRFallProt] = 0
                        theSet2![IRFlam] = 0
                        theSet2![IRFireProt] = 0
                        theSet2![IRVeh] = 0
                        theSet2![IRTools] = 0
                        theSet2![IRHousekeeping] = 0
                        theSet2![IRFirstaid] = 0
                        theSet2![IRWelding] = 0
                        theSet2![GetQues] = 0
                        theSet2![ContactFirstName] = Forms![frmLoc].[FirstName]
                        theSet2![ContactLastName] = Forms![frmLoc].[LastName]
                        theSet2![ContactTitle] = Forms![frmLoc].[Title]
                        theSet2![AppTrackingID] = theAppTrIDPrep
                        theSet2.Update
                        theSet2.Close
                       
                    theIDPrep2 = DMax("[AppID]", "tblAppt") + 1
                    theAppTrIDPrep2 = DMax("[AppTrackingID]", "tblAppt_Tracking") + 1
                   
                        Set theSet3 = CurrentDb.OpenRecordset("tblAppt")
                        theSet3.AddNew
                        theSet3![LocID] = Forms![frmLoc].[LocID]
                        theSet3![AppType] = "Training Set Up"
                        theSet3![EnteredBy] = DLookup("[UserID]", "temp_Users")
                        theSet3![EnteredDate] = Date
                        theSet3![EnteredTime] = Time
                        theSet3![AppID] = theIDPrep2
                        theSet3.Update
                        theSet3.Close
                       
                        Set theSet4 = CurrentDb.OpenRecordset("tblAppt_Tracking")
                        theSet4.AddNew
                        theSet4![AppID] = theIDPrep2
                        theSet4![JobStatusText] = "Scheduled"
                        theSet4![AppDate] = Me.AppDate
                        theSet4![InspectorName] = Me.[InspectorName]
                        theSet4![AppTimeSlot] = adjAppTimeSlot
                        theSet4![AppDuration] = "1.0 Hr"
                        theSet4![IRTruckTrlr] = 0
                        theSet4![IRElec] = 0
                        theSet4![IRGenInd] = 0
                        theSet4![IRStorage] = 0
                        theSet4![IRExcav] = 0
                        theSet4![IRMaint] = 0
                        theSet4![IRMatStorage] = 0
                        theSet4![IRHvyEquip] = 0
                        theSet4![IRProtEquip] = 0
                        theSet4![IRConfSpace] = 0
                        theSet4![IRScaffolds] = 0
                        theSet4![IRLadders] = 0
                        theSet4![IRWkZone] = 0
                        theSet4![IRMisc] = 0
                        theSet4![IRFallProt] = 0
                        theSet4![IRFlam] = 0
                        theSet4![IRFireProt] = 0
                        theSet4![IRVeh] = 0
                        theSet4![IRTools] = 0
                        theSet4![IRHousekeeping] = 0
                        theSet4![IRFirstaid] = 0
                        theSet4![IRWelding] = 0
                        theSet4![GetQues] = 0
                        theSet4![ContactFirstName] = Forms![frmLoc].[FirstName]
                        theSet4![ContactLastName] = Forms![frmLoc].[LastName]
                        theSet4![ContactTitle] = Forms![frmLoc].[Title]
                        theSet4![AppTrackingID] = theAppTrIDPrep2
                        theSet4.Update
                        theSet4.Close
                       
                    End If
                   
                End If
               
    If Me.AppNew = "New" Then
        Me.AppNew = ""
    End If
   
    If IsOpen("frmLoc") Then
        Forms!frmLoc!frmLoc_Sub_ApptTr.Requery
    End If

    DoCmd.Close acForm, Me.Name, acSaveYes
 
Exit_cmdEditApptTrSaveAndClose_Click:
    Exit Sub

Err_cmdEditApptTrSaveAndClose_Click:
    MsgBox Err.Description
    Resume Exit_cmdEditApptTrSaveAndClose_Click
End Sub