.net - InvalidCastException Was Unhandled?
Apr 4, 2012
Dim CustID As String = txtSrchCustID.Text
Dim FirstName As String = txtNewCustFName.Text
Dim SecondName As String = txtNewCustSName.Text
If CustID And FirstName And SecondName = "" Then
MsgBox("Please enter a term to search by")
EndIf
This returns "Conversion from string "" to type 'Long' is not valid." I was wondering what the error is and how it's possible to fix it? The other questions that I've looked at were mostly to do with variables assigned incorrect types, but I think that isn't the issue. It occurs when all of the variables are empty.
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Oct 30, 2009
OK, this is going better, now im stuck in the mud again, i am trying to get a form to print,this works now, however i would like to enable a few frames with text boxes for a few seconds to allow the printer to print the text in black instead of gray. he error i am getting is this, as the timer disables:" Unable to cast object of type System.Windows.Forms.Timer' to type 'System.Windows.Forms.ToolStripMenuItem'. "
Public
Sub
Print_Renamed_Click(ByVal
[code].....
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May 15, 2011
Private Sub gvDesignGVnote_CellClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles gvDesignGVnote.CellClick
If e.RowIndex < 0 Then[code]......
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May 17, 2012
I am making a simple calculator and it's saying InvalidCastException was unhandled when I try to debug it, here's the code, please tell me whats wrong with it: (and yes I have renamed the textboxes to addequals etc...
Public Class Form1
Private Sub WebBrowser1_DocumentCompleted(ByVal sender As System.Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs)
End Sub
[code].....
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Apr 12, 2012
I have some trouble in SMS gateway project using VB.Net (VS 2010)while programme was running, I found error "InvalidCastException was Unhandled", then my programme cannot continue. below I copy the code of the programme :
----------------------------------------------------------------------------------------------------------------------
Option Explicit On
Public Class MessageReceiver
Private TPMessageTime As String
[code]....
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Oct 19, 2011
I am trying to get a 3rd party activex control which works in VB6 to work in Visual Studio 2005. Using the same exact code I am receiving an InvalidCastException error. Specified cast is not valid.
The code is as follows: AxQIChartControl1.DataTable =
"A-Filler"
AxQIChartControl1.Columns =
"Weight"
AxQIChartControl1.ChartType = 2
[Code]...
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Apr 25, 2012
below is my piece of code where I click on "Edit button" then retrieve the data from access database so that I edit them on a form.
This is what I get when I click on edit: InvalidCastException was unhandled and highlights the line below The UserID contain Alphanumeric characters.
'check for the selected item in list
If lvUsersList.SelectedItems.Count > 0 Then
If Me.lvUsersList.SelectedItems.Count > 0 Then
[Code].....
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Dec 10, 2011
I use this code to populate combobox1&2:
'Main form on load events
Private Sub frm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
[Code]....
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Feb 26, 2012
I'm a beginner to Visual Basic. In here I want to recreate a piggy bank which tells me how much money do I have. I created a function but the program tells me :
[Code]...
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Nov 2, 2010
I'm implementing following code in VS2010:
If xl.cells(1, contacolonna).Borders(Excel.XlBordersIndex.xlEdgeRight).LineStyle <> Excel.XlLineStyle.xlContinuous Then
MsgBox("hello")
End If
or following
[code]....
but in both cases VS returns following error:"InvalidCastException was unhandled Overload resolution failed because no Public '=' can be called with these arguments:'Public Shared Operator =(a As String, b As String) As Boolean':Argument matching parameter 'a' cannot convert from '__ComObject' to 'String'. "
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Jul 16, 2010
why I got the following (InvalidCastException was unhandled) on the following code and how can I solve the problem.
LabelPB.Text = P - Total.Text 'Conversion from string "" to type 'Double' is not valid
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Jan 13, 2011
I have just upgraded to Microsoft Visual Basis 2010 Express (Running on Vista and Microsoft Office Excel 2007). The last time I used VB was about 5 years ago and was v5.0 I am trying to do the very simple action of opening a spreadsheet using VB and reading in cell values into two text boxes (I am using an example posted on the web to ensure my approach is correct). The run fails at the point:
[Code]...
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Apr 9, 2010
I have a field named 'UserID' in my OLE database with the type 'Autonumber'. But when I try to cast it to a variable of type 'String' I get an an InvalidCastException - Specified cast is not value.
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Aug 15, 2010
I'm using a C# API wrapper library for connection to a program. It has worked very well for a long time, but now I have this error I can not get out of. The error occurs inside the library code (which I have not modified). It gives the following pop-up window:I believe I had this or similar type of error some times before (at least the first pop up was similar), and then I believe I just clicked "Build solution", or rebuild, and it would work. But this time not...
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Sep 29, 2010
I am using Visual Studio 2005, Version 2.0. Coding a windows application with VB.NET.I am trying to use a textbox (txtLogCall) to display matched results in a datagrid. I have added a bindingsource and have the dataset and tableadapter.
I have set the databinding tag of the datagrid to the field that I want to use as a parameter. The textbox is for an Caller's Name, so I have set the datagrid tag to 'EmergencyCallerIdentification' that is in the table.
[Code]...
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Dec 12, 2010
I have a Linq Group By query that works. Here's the query:
Dim query = From fb As Feedback In lst Where fb.Seller.login_name.ToLower = UserName.ToLower
Order By fb.transaction_id Descending, fb.creation Descending _
[Code]...
I don't like working with anonymous types so I'm trying to delare the result and am hitting an InvalidCastException.
Here's the type information:
Debug.Print(query.GetType.ToString)
Returns:
System.Linq.GroupedEnumerable`4[Feedback,System.Nullable`1[System.Int32],Feedback,VB$AnonymousType_0`2[System.Nullable`1[System.Int32],System.Collections.Generic.IEnumerable`1[Feedback]]]
[Code].....
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Aug 12, 2011
I have a Linq Group By query that works. Here's the query:
Dim query = From fb As Feedback In lst Where fb.Seller.login_name.ToLower = UserName.ToLower
Order By fb.transaction_id Descending, fb.creation Descending _
Group fb By fb.transaction_id _
Into Group
I don't like working with anonymous types so I'm trying to delare the result and am hitting an InvalidCastException.
Here's the type information:
Debug.Print(query.GetType.ToString)
Returns:
System.Linq.GroupedEnumerable`4[Feedback,System.Nullable`1[System.Int32],Feedback,VB$AnonymousType_0`2[System.Nullable`1[System.Int32],System.Collections.Generic.IEnumerable`1[Feedback]]]
and the inner type:
Debug.Print(item.GetType.ToString)
Returns:
VB$AnonymousType_0`2[System.Nullable`1[System.Int32],System.Collections.Generic.IEnumerable`1[Feedback]]
So, armed with this information, here's the declaration used:
Dim query As IEnumerable(Of IGrouping(Of Int32?, IEnumerable(Of Feedback)))
Here's the error returned:
Unable to cast object of type 'System.Linq.GroupedEnumerable`4[Feedback,System.Nullable`1[System.Int32],Feedback,VB$AnonymousType_0`2[System.Nullable`1[System.Int32],System.Collections.Generic.IEnumerable`1[Feedback]]]' to type
[code]....
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Aug 15, 2011
I am trying to catch the System.InvalidCastException error. If I put a number into the calculator the program runs ok. If the calculate button is pressed with nothing in the text boxes I get the casting error Conversion from string "" to type 'Decimal' is not valid. I understand why I am getting the error. I don't know what to do about it. I want the program to dump null data and go back to waiting for input from the user.
Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim FedTaxRate = 0.13 ' constants for taxes and work week
[code].....
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Apr 20, 2011
I'm programming a slideshow in Visual basic and get a SystemInvalidCastException when trying to initialize an array through a For Each loop. Here's what I'm trying to do. I have an array of Images() and another array of ImageNames(). Now I store all my images on a website, let's sa so for ease of use, I've named all my images in this manner
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Sep 12, 2011
I've got a typed dataset. I bind the data with a binding source to a form with arround 200 textboxes, dataedits and so on. Everything works fine with one exception:In my database I have empty DateTimes (DBNull.Value). And when they get bound to a DateEdit-Control, I get the following exceptions:
A first chance exception of type 'System.InvalidCastException' occurred in Microsoft.VisualBasic.dll
A first chance exception of type 'System.Data.StrongTypingException' occurred in myTestDLL.dll
I tried to change the NullValue-Property in the DataSet-Desinger to something else as 'Throw Exception', but it doesn't work for a DateTime. For other types like Integer or String it works fine.I dont know a nice solution (right now I fill the empty dates with some dummy date and make it invisible in the DateEdit-Control, but this is very uncool) and I hope to find some help here.
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Jan 21, 2011
I get the correct numbers out of the variable(in this case 11) but i cannot compare it bcuz i get this error. both values are int, cannot seem to find the problem.
Dim id = CInt(Request.QueryString("id"))
Dim uk = From hj In dc.Orders _
Where hj.UserID = id _
Select hj
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Mar 3, 2010
I'm trying to Parse dates entered into a TextBox into a DateTime value but I keep getting an exception in the TryParseExact method. What I'm trying to do is: DateTime.TryParseExact(tbAddDate.Text.Trim, "yyMMdd", New CultureInfo("sv-SE"), DateTimeStyles.None, row.Date)
This throws an InvalidCastException with the message "Conversion from type 'DBNull' to type 'Date' is not valid." I realize what is happening is that it's trying to set row.Date to DBNull which is not a valid value for a DateTime. What I don't understand is why it's trying to do this, as the documentation states that it should be set to MinValue and not DBNull.
As a sidenote, I know that I can get around a lot of these problems by using a DateTimePicker but the customer feels that they are very clunky as it's not possible to enter the dates directly with the keyboard.
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Oct 15, 2008
There is a class in this datalayer that subclasses System.Data.Datatable. So for example if I populated a System.Data.Dataset and then tried to put the first table of this dataset into this class like so:
Code:
Dim dt as new myDatable
dt = ds.Tables(0)
[code]....
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May 7, 2010
Visual Basic 2008 I'm trying to delete a row from an Access database in my DataGridView using a coded delete button. I have an input box asking for a row number to delete. It works fine except if I have anything but an interger, leave the input blank, or hit the cancel, I get :
[Code]...
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Sep 10, 2010
The following line is giving me an InvalidCastException when trying to convert to IEnumerable type, even though I have implemented IEnumerable interface. Return New CountryInfo(CountryCodes(i), CountryNames(i)) (also in bold below)
Imports System
Imports Gaia.WebWidgets.HtmlFormatting
Imports System.Collections.Generic
Imports System.Globalization
[code]....
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Dec 16, 2009
[URL]The answer to the above question was to use a series of javascript calls as URL's in order to fill in a web form and submit it. I have been trying to do this automatically inside a VB .NET program with no success.The original example I was given doesn't work, presumably because you are waiting on the same thread as that in which the WebBrowser control is working:
WebBrowser1.Navigate("http://www.google.com")
Do While WebBrowser1.IsBusy OrElse WebBrowser1.ReadyState <> WebBrowserReadyState.Complete
Threading.Thread.Sleep(1000)
[code]....
The curious thing is that the check of ReadyState (or IsBusy, for that matter) in the wait loop will sometimes throw a InvalidCastException. Presumably calls to these are not thread safe? I have no idea. If I put the offending call inside a Try block, the wait loop just fails to work. In fact, it even seems the exception "persists" to screw everything up, because even stepping through the code with the try block Visual Studio freezes for a good 10 to 20 seconds (it does the same without the try block).
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Aug 30, 2010
I am developing a fairly comprehensive Excel add-in, applying a lot of ops. Take a workbook, save under new name, apply actions (add names, change formulae, etc). Generally it works fine, but from time to time .Net throws an InvalidCastException on virtually any of my CTypes. When I acknowledge the error and run the code again (without quitting Excel) on the exact same Excel workbook, no error occurs. The InvalidCastException occurs maybe in 40% of all tries, otherwise the add-in succeeds.
[Code]....
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May 18, 2012
I'm working on setting up a large set of stored procedures using SQL CLR. I'm currently in debugging mode. I'm trying to write a data set back to the client using SqlPipe.
[Code]...
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Feb 20, 2012
I use code such as this to clear out the values in several text boxes: Private Sub RibbonButtonInsert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RibbonButtonInsert.Click
[Code]...
Because the date picker control did not clear out like the other controls did, I tried:
DatePickerDateOfBirth.Value = ""
but it does not clear out. Instead, I get an "InvalidCastException". show me what coding I need to properly clear out the value in this data picker?
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Oct 13, 2009
I have a C# library that internal clients configure with VB.Net Their scripts are throwing an InvalidCastException where they really shouldn't.
So the code is something like this (massively simplified):
//C#3
public class Foo {
public static implicit operator Foo ( Bar input )
[Code].....
Strange - it looks like the VB.net compiler can find the cast operator but it's lost at runtime. Surely the VB and C# IL will be pretty similar here?
The VB.net code is dynamically compiled - the compile happens the first time a user logs into the app. it's being compiled as VB.Net against .Net 3.5, and I'm not using any COM interop.
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