Hello Samir Vaidya,
Please make sure your hosting provider fulfills all system requirements of Sitefinity which can be found in our documentation. Also check whether the project has all dlls in the bin folder and reference to them. This error might occur if you have rebuild the project which removes the dlls from the bin folder.
As I read from your other ticket, your shared hosting company does not support Sitefinity 4.x due to the fact that they cannot provide enough memory for the Application Pool on which Sitefinity is hosted. I would like to advise you to use check our shared hosting partners page
, where you can find all shared hosting companies which fully support Sitefinity 4.x.
the Telerik team
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