Technote Details :: Repairing the includes folder
Issue
After performing an update, when I try to preview a page in the Browser, I get an error message saying "Fatal error: Class tng_multipleinsert: Cannot inherit from undefined class tng_multiple".
Reason
This happens because not all of the files in the includes folder were uploaded to the server, or some files were changed by the update. Because of this, class definitions stored in some files are not found when requested by your pages.
Solution
To completely correct this problem, it is recommended that you delete the includes folder on the server (making sure you preserve your custom created skins, internationalized resources, or any other personally modified files in the folder) and re-uploading it from the locally generated version.