SYMPTOMS

Composing a message within web mail using the lightweight editor may produce the following error below:

FreeTextBox has not been correctly installed. To install FreeTextBox either:
(1) add a reference to FtbWebResource.axd in web.config:
<system.web>
<httpHandlers>
<add verb="GET"
path="FtbWebResource.axd"
type="FreeTextBoxControls.AssemblyResourceHandler, FreeTextBox" />
</httpHandlers>
</system.web>

(2) Save the FreeTextBox image and javascript files to a location on your website and set up FreeTextBox as follows
<FTB:FreeTextBox id="FreeTextBox1" SupportFolder="ftbfileslocation" JavaScriptLocation="ExternalFile" ButtonImagesLocation="ExternalFile" ToolbarImagesLocation="ExternalFile" ButtonImagesLocation="ExternalFile" runat="server" />

CAUSE

Incorrect verb settings for the .axd mapping under the root website. Or under the .axd maping of the web mail virtual directory. 

RESOLUTION

1. Navigate to IIS manager

2. Locate the web site that the web mail interface is being accessed on

3. Right click and access the properties window for the web site and navigate to the "Home directory" tab

4. Select the "configuration" button and then navigate to "app mappings". In the mappings list, locate the .axd mapping then click on the .axd in the list to select it. Hit the "Edit" button to open its properties window.

5. In the "edit" window ensure the following settings are configured:

    a. Under verbs section ensure that it is set to "limit to:" and the verbs are GET,HEAD,POST,DEBUG

    b. Ensure that the option "verify that file exists" is turned off.