Warning: Error in

After I deploy my R shiny App in web server, it produced such errors. Can anyone help me to solve it? Thanks. This error is very weird. I can run it in Shiny web server (http://www.shinyapps.io/). But I can not run it on my own web server.

I commented out the code which produce pdf. But the error is still existing.

su: ignore --preserve-environment, it's mutually exclusive to --login.

Listening on http://127.0.0.1:37436 Warning: Error in : cannot open file 'Rplots.pdf' 48:

Execution halted