Solved: “Unrecognized tag prefix or device filter ‘telerik'”

I came across “unrecognized tag prefix” error while trying to use Telerik’s ASP.NET AJAX controls. Here is how the error message looks like:

Warning – Unrecognized tag prefix or device filter ‘telerik’


  1. Make sure to add Telerik DLLs into the bin folder of your project
  2. Add the following handlers into your web.config file (in section):

          <add path="ChartImage.axd" type="Telerik.Web.UI.ChartHttpHandler" verb="*" validate="false"/>
          <add path="Telerik.Web.UI.SpellCheckHandler.axd" type="Telerik.Web.UI.SpellCheckHandler" verb="*" validate="false"/>
          <add path="Telerik.Web.UI.DialogHandler.aspx" type="Telerik.Web.UI.DialogHandler" verb="*" validate="false"/>
          <add path="Telerik.RadUploadProgressHandler.ashx" type="Telerik.Web.UI.RadUploadProgressHandler" verb="*" validate="false"/>
          <add path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" validate="false"/>

Similar solutions apply to the same type of message for other components.

How to use Oracle “OPatch Utility” to find out information about Oracle Home

Oracle has a useful tool to list information about its products: OPatch Utility. You can apply patches or get information about the installed updates by using this command line tool.

One of the commands that come with this tool is lsinventory. It lists the patches applied to Oracle Home.


  1. Search for “OPatch” in Windows
    There might be several folders with this name if you have installed Oracle Data Access Components (ODAC) more than once
  2. Open command prompt in the actively used “OPatch” fodler
  3. Run the command below
opatch lsinventory


How to record your computer’s screen for free?

When it comes to screen recording, Camtasia is the first that comes to the mind. However, popularity comes with a price. You can use Camtasia for 30 days for free but then the charge is $199!

I have been looking for a free and easy to use desktop application to record my screen. Icecream Screen Recorder gets the job done easily.

It can record the entire screen or an are you select. The free version can record up to 5 minutes. If you want to record longer videos, PRO version is $30.