Hi debu, I don't think we have enough information to help you.
The cannot open the connection frequently means you have some code that is trying to open a file, but is unable to because the appropriate file path is not provided.
The shiny team put together the following guides to help debug your shiny app here: Debugging Shiny applications.
In order to efficiently get help in a forum like this, it's useful to package your question as a reproducible example (reprex). Here's a handy guide with tips to ask a shiny reprex: Shiny debugging and reprex guide