Error message: Object reference not set to an instance of an object.

Stack trace:    at Telerik.Web.UI.RadComboBox.OnInit(EventArgs e)

   at System.Web.UI.Control.InitRecursive(Control namingContainer)

   at System.Web.UI.Control.AddedControl(Control control, Int32 index)

   at Telerik.Web.UI.GridPagerItem.InitializePagerItem(GridColumn[] columns)

   at Telerik.Web.UI.GridPagerItem.SetupItem(Boolean dataBind, Object dataItem, GridColumn[] columns, ControlCollection rows)

   at Telerik.Web.UI.GridTableView.CreateTopPagerItem(Boolean useDataSource, GridColumn[] copiedColumnSet, Boolean isPagingEnabled, GridTHead thead)

   at Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource)

   at Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource)

   at System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls()

   at System.Web.UI.Control.EnsureChildControls()

   at Telerik.Web.UI.GridTableView.get_Items()

   at Telerik.Web.UI.GridTableView.GetSelectedItems()

   at XXX.StudentSearch_PreRender(Object sender, EventArgs e) in C:\XXX\StudentSearch.aspx.vb:line 140

   at System.EventHandler.Invoke(Object sender, EventArgs e)

   at System.Web.UI.Control.PreRenderRecursiveInternal()

   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

We are exporting our webpage to a PDF using RadClientExportManager. There are two <img> on the webpage, one is included in the downloaded PDF, but one is not on the PDF. The one that is on the PDF has it's "src" set in the HTML tag, and the image that is not showing up on the PDF has its source set in the code behind from an API call.

Image that is working:

<img src="~/Logo.png" runat="server" height="120" align="Right"/>

Image that is not working:

HTML:

<img id="imgProfilePicture" runat="server" align="left"/>

VB.net:

imgProfilePicture.Src = API_Call.SelectToken("e[10].image_url")
imgProfilePicture.Height = 120

Both images are visible on the website, just not on the downloaded PDF.

Any help would be appreciated, thank you.

Hi everybody,
I am using telerik.web.ui 2016 version for ASP.NET website. How can I upgrade to R1 2023 SP1 version in .NET framework 4.0. I see the new version has added key validation in IIS . I don't know where to start.
We wish everyone help!

Steps:

1. Go to Telerik Web UI MultiColumnComboBox WebForms MultiColumnComboBox Overview Demo | Telerik UI for ASP.NET AJAX

2. Enter "ha" select some records

3. Click out of the dropdown to close it

4. Textbox keeps "ha" but the message below reads that You have selected Thomas Hardy whose ID is AROUT. They are a Sales Representative at Around the Horn however, nothing has been selected.

Is it expected ?
If it's a bug and having a long cycle to fixing bugs could you recommend any workaround?

Hi, I have a Timeline view RadScheduler, and I would like to access some of the cells based on resource name and time slot.
Please see the image for reference.
I searched forums and most questions are about how to set the background color of time slots, and I checked documentation the time slot represents the whole row/column of a specific time for all resources. But in my case I only want to set the time slot of specified resource, aka a single cell or coulple of cells.
Could anyone help me?

I am using a RadTextBox for a simple messaging form, and if the user leaves a field blank, I use a CustomValidator to set the control IsValid=true.  This is great and it uses the invalid style (pink background) and little icon and brings the user's attention to the field.

protected void valMissingFields_ServerValidate(object source, ServerValidateEventArgs args)
{
    txtMessageSubject.Text = txtMessageSubject.Text.Trim();
    txtMessageBody.Text = txtMessageBody.Text.Trim();

    txtMessageSubject.Invalid = (txtMessageSubject.Text == "");
    txtMessageBody.Invalid = (txtMessageBody.Text == "");

    args.IsValid = (!txtMessageSubject.Invalid && !txtMessageBody.Invalid);
}

I thought the InvalidStyleDuration would make it go away after a few seconds (3000 ms = 3 seconds):

<table cellspacing="0" cellpadding="0" style="width:100%;">
    <tr valign="top">
        <td style="width:90px;">
            Message:
        </td>
        <td>
            <telerik:RadTextBox ID="txtMessageBody" runat="server" 
                Width="100%" MaxLength="1000" TextMode="MultiLine" Rows="25" 
                InvalidStyleDuration="3000" 
                EnableEmbeddedSkins="false" Skin="MyCustomSkin"></telerik:RadTextBox><br />
        </td>
        <td style="width:20px; text-align:right;">
            <span class="required">*</span>
        </td>
    </tr>
</table>

But it does not.

Instead, the user is stuck typing into the text box with bright red bold lettering.  

Am I misunderstanding how this works?

As a workaround, I thought I'd use the OnClientEvents for OnValueChanging to make it switch the Invalid indication off, but apparently that event only fires when focus moves away from the control.

I'm using the RadSpreadsheet component and saving it's content following this instructions here:

Telerik RadControls Access the Spreadsheet workbook on the server - Telerik UI for ASP.NET AJAX

So, my code behind is like this:

protected void Page_Load(object sender, EventArgs e)
{
    if (Page.IsCallback && Request.Params["__CALLBACKID"] == RadSpreadsheet1.UniqueID)
    {
        Workbook workbook = Telerik.Web.Spreadsheet.Workbook.FromJson(Request.Params["__CALLBACKPARAM"]);
        SaveWorkBook(workbook);
    }

}

With this code I'm able to save the spreadsheet just fine. But it's not saving the images I add using the Insert Image button (from telerik component). The images are simply not being passed through.

How can I work around that? Thank you!