An unhandled Microsoft .Net Framework exception occurred in w3wp.exe Error SharePoint

Hello Team,

We have SharePoint application with some custom approval code not using workflows.

The application was running fine but now when we are doing a post back from on of the button click we are getting following error

"An unhandled Microsoft .Net Framework exception occurred in w3wp.exe Error" on the server.

We refered many articles on the internet , there is no update happened in .Net framework or in app pool identity.

Could you please help us.

Thanks.

VINAYAK BHANGALE