SharePoint Error type is not registered as safe

Question

I've to update Sharepoint 2007 to Sharepoint2010 for which in place upgrade was not possible then I went to another solution to copy content database of my web application from 2007 server to SP2010 server now my site is working ok but my webpart from older site are not working it throws the error

'SharePointCustomizations.TMS.TravelRequest.CustomForm' is not allowed for this page. The type is not registered as safe.

and in source error it says

<%@ Page 
     EnableSessionState="True" 
     Language="C#" 

my question is why this 'SharePointCustomizations.TMS.TravelRequest.CustomForm' form is not available and why it not opening in SP2010

Please have a look in attached image for better understanding

Answer 1

I found the solution by just adding SafeControl tag inside my WebConfig File

  <SafeControl Assembly="SharePointCustomizations.TMS, Namespace="SharePointCustomizations.TMS.WebForms" TypeName="*" Safe="True" AllowRemoteDesigner="True" />

Safe="True" is very important ;) These tags made this error go away.