Last Updated: 13 Feb 2024 09:35 by ADMIN
In R3 2016 SP1 when a RadEditor with RenderMode=Classic is disposed and RadScriptManager is used, a JavaScript error is thrown:
IE:  Object doesn't support property or method 'dispose'
Chrome: Uncaught TypeError: this._contextMenuFunctionality.dispose is not a function

FIXED in R3 2016 SP2 (2016.3.1027)

There are three workarounds:
- Set EnableScriptCombine to false for the RadScriptManager (not applicable when CDN is used)
- OR set RenderMode=Lightweight for the RadEditor (you can do this in the web.config for all control instance in the web app if they do not define the Classic mode exiplicitly)
- OR add the following function override at the end of your page:

			<telerik:RadScriptManager ID="RadScriptManager1" runat="server" >

			<%-- WORKAROUND 1: SET EnableScriptCombine="false" TO RADSCRIPTMANAGER--%>

			<asp:Button ID="Button1" Text="click to postback and break the editor" runat="server" />

			<telerik:RadEditor ID="txtInstructions" runat="server">

			<%-- WORKAROUND 2: SET RenderMode="Lightweight" TO RADEDITOR--%>


				Telerik.Web.UI.Editor.DefaultToolAdapter.prototype.dispose = function ()
					delete this._fakeToolbarParentCreated;
					var toolbars = this._getToolBarElements();
					if (toolbars) {
						for (var i = 0; i < toolbars.length; i++) {
					this._tools = [];
					var wnd = this._toolbarHolder;
					if (wnd && wnd.dispose) wnd.dispose();
					var contextMenuFunctionality = this._contextMenuFunctionality;
					if (contextMenuFunctionality && contextMenuFunctionality.dispose) contextMenuFunctionality.dispose();
					Telerik.Web.UI.Editor.DefaultToolAdapter.callBaseMethod(this, "dispose");
Last Updated: 16 Jan 2024 11:46 by ADMIN
Release 2024 Q1
1.       Visit the RadEditor demo at (I used Google Chrome.)

2.       In the HTML view, replace the entire demo text with

This <strong>strange</strong> thing

3.       In the Design view, place the cursor at the very end of the line, and press Shift+Left repeatedly.

a.       At first it will highlight the final letter correctly.

b.      Then it will UNHIGHLIGHT the final letter!

c.       Then it will begin highlight more letters again starting from the letter BEFORE the final letter.

d.      Then, after highlighting the ā€œeā€ in strange, it will being UNHIGHLIGHTING starting from the righthand side of the selection!

e.      Then it will highlight left as far as the ā€œsā€.

f.        Then it will start UNHIGHLIGHTING from the right again!

g.       Then highlighting the space to the left

h.      Then UNHIGHLIGHTING the space to the left!

i.         Then highlighting to the left as far as the beginning of the line

j.        Then UNHIGHLIGHTING from the right side of the selection!

Pressing Shift+Left and Shift+Right should always modify only one end of the selection, and the other end should always remain where the selection was started. This is how Windows Notepad and virtually all other applications behave.
Last Updated: 16 Jan 2024 11:44 by ADMIN
Release 2024 Q1
Created by: JP
Comments: 1
Category: Editor
Type: Bug Report

Steps to reproduce the text highlighting issue:

  1. Go to
  2. Delete the content and write a single line
  3. Use the mouse to highlight a portion of text starting at the end (right side) of the text and dragging toward the beginning (left side).
  4. Stop about halfway to the beginning of the text.
  5. Now, while the text is still highlighted, press shift and left arrow to continue selecting. This will work for some time until the highlight gets near the beginning, then, the highlight will start moving from the right side.
Last Updated: 26 Sep 2023 08:45 by ADMIN

There are issues with the cursor location when clicking at the end (or to the right) of a line in bullet lists with multiple levels.

When clicking at the end of the line the cursor is unexpectedly placed at the beginning of the line instead of at the end.

This does not happen if you click on some of the actual text or hit the exact location of the last character of the line, but when you naturally click just to the right of the end of the line.

It seems that it does not happen on all levels, but only some, as I have tried to depict in the attached screenshot.

This behavior was replicated on the latest WebForms Editor demo at

Last Updated: 26 Jun 2023 20:50 by Sai
Release R2 2023 SP1

Uncaught TypeError: Failed to execute 'createObjectURL' on 'URL': Overload resolution failed error is thrown when pasting an image or a chart image from MS Word in RadEditor in Chrome / MS Edge.

The problem can be reproduced in the live demos too:

The error also prevents the execution of the OnClientPasteHtml event of the control.


Last Updated: 01 Jun 2023 08:01 by ADMIN
RadEditor disappears after loading content through ajax manager and SelectedIndexChanged of a regular asp:dropdownlist and iframe content area mode (Safari Only)
Last Updated: 30 Mar 2023 15:53 by ADMIN
Release R1 2023 SP1

The XHTML validator in the editor control is not working.

As per attached screenshot, when you click it and opens the window it simply states the following.

"Sorry! This document cannot be checked."

"Sorry, this type of URL scheme (undefined) is not supported by this service. Please check that you entered the URL correctly"

Can someone tell me why this is happening? It's also broken on the editor demos on your site. Maybe something on the W3C validator has changed making it no longer compatible/viable? 

Last Updated: 30 Mar 2023 15:50 by ADMIN
Release R2 2023
Whether the editor has content, or has no content, the XHTML validator always gives the same errors as per the attached screenshot.   
Last Updated: 24 Mar 2023 15:20 by ADMIN
Release R1 2023 SP1

The editor does not work at all in Chrome for iOS.

You can reproduce it in this demo:




Last Updated: 28 Feb 2023 13:51 by ADMIN

Using the latest 2022.3.1109.45, our web application is catching "Invalid Resource Request" exceptions when the Windows7 or Vista (maybe others too) loads the "Editor" control in "Classic" mode.    By decoding the URL, the control is having problems locating the image below

Error Message: This is an invalid webresource request.



Change the skin of the radeditor in the default.aspx to another skin such as "metro" and the problem will not happen.    It works OK at least on Black, Metro and Silk but haven't tested others, you can tell it doesn't work when the divider bars in the editor toolbar don't appear properly.

Last Updated: 21 Nov 2022 14:46 by ADMIN
In earlier versions of the editor, the css class was applied to the image tag itself, which is the correct way to do it. Otherwise the applied css class has no effect on the image.
Last Updated: 05 Sep 2022 10:43 by ADMIN
Release R3 2022
Clear content;
Add a table;
Open context menu by selecting a cell in the table;
Open Cell Properties;
Open More cell Styling;
Chose Background color;
Change it and click OK
Click OK in Table Wizard.
Actual: No background color is applied. 
Last Updated: 29 Jun 2022 12:28 by ADMIN
Release R3 2022

Please follow these steps to reproduce the issue: 1. Open RadEditor Demo: 2. Choose a word that is present in the text (e.g. "Barcelona"). 3. Open "Find And Replace" dialog. 4. Click on the "Replace" tab. 5. Write "Barcelona" or any other chosen word in the "Find" field. 6. Write something in the "Replace With" field (e.g. "Replacement"). 7. Select the "Up" Direction in "Search Options". 8. Click "Replace All". Actual Result: The "The search string was not found." message is displayed and the substrings ("Barcelona") are not replaced. Expected Result: All occurrences of the substring are replaced. Note that this functionality seems to be working if the "Down" direction is chosen.

Update: I would like to add that the issue is not only with Replace All. The same bug is happening with "Replace" with both "Up" and Down" directions.

Last Updated: 29 Jun 2022 09:45 by ADMIN

The execution of the getContextMenuByTagName inside the oncontextmenu event of RadEditor hides the context menu once it is shown. This happens in Lightweight render mode only and when the UseRadContextMenu is enabled:

<telerik:RadEditor ID="RadEditor1" runat="server" ContentAreaMode="iframe" OnClientLoad="OnClientLoad">
    function OnClientLoad(editor, args) {
        editor.attachEventHandler("oncontextmenu", function (e) {
            var oSelection = editor.getSelectedElement();

            setTimeout(function () {
                var tdMenu = editor.getContextMenuByTagName("TD"); //the call of getContextMenuByTagName closes the context menu when lightweight render mode is used. You can slow down the closing with the setTimeout function or by settign UseRadContextMenu to false.

            }, 1000);


Last Updated: 24 Jun 2022 13:56 by ADMIN
Release R3 2022
Created by: Rumen
Comments: 2
Category: Editor
Type: Bug Report
"The size of the uploaded file exceeds max size allowed" is thrown even if the file is under the specified maximum upload file size.

The error is reproducible in the Default demo ->

Open the Document manager and upload some unsupported file which size does not exceed 200 kb. For example upload a small image file. You'll get the following error:

The size of the uploaded file exceeds max size allowed.
The extension of the uploaded file is not valid. Please, provide a valid file!

while only this line should be shown: The extension of the uploaded file is not valid. Please, provide a valid file!
Last Updated: 22 Jun 2022 12:34 by ADMIN
Pressing ENTER over a list item not only creates a new li, but also inserts additional <br> element.


Steps to reproduce:
1. Open in Chrome:
2. Switch to Html mode and insert the following content:
    <li>123 456

3. Switch to design mode
4. Put the cursor inside the first li (e.g. before 5) and press ENTER

Result: A <br> element is added in the beginning of the new <li> element
Last Updated: 21 Jun 2022 22:53 by ADMIN
It should rather select the last cell of the table. 
Last Updated: 21 Jun 2022 22:34 by ADMIN
When using Table Wizard to insert a new table inside a table cell, the selected table is replaced by the one created from Table Wizard. 

Currently, the workaround is to use the plain InsertTable tool in order to nest tables. 
Last Updated: 21 Jun 2022 22:34 by ADMIN
Last Updated: 21 Jun 2022 15:13 by ADMIN
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