Hi there, and welcome to community.rstudio.com! It's a little hard to help with only a screenshot to go on and no code. To help you get the right help for your question, can you please turn it into a reprex (reproducible example)? This will ensure we're all looking at the same data and code. A guide for debugging Shiny apps and creating a Shiny reprex can be found here.
I will echo what @ksavin has said about checking the logs - the user-facing error messages are pretty generic.