I tested RadFileExplroer with the provided snippet, but the dropdown was properly added at my end. Can you, please, share some more details about the scenario in which the error is thrown?
- What was version of the controls you were using prior the upgrade to R1 2020?
- In which moment of the page life-cycle are you configuring the Toolbar?
- Can you send me a simple page containing the setup needed to replicate the problem?
Below you can see the setup I used for my test:
<telerik:RadFileExplorer RenderMode="Lightweight" runat="server" ID="FileExplorer1" Width="595px" Height="350px"
<Configuration EnableAsyncUpload="true" ViewPaths="~/FileExplorer/Examples/Overview/images"
Protected Sub Page_Load(sender As Object, e As EventArgs)
Dim dropDown As RadToolBarDropDown = New RadToolBarDropDown("PageSize")
dropDown.CssClass = "perPageDropDown"
dropDown.EnableImageSprite = False
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