Shiny server suddenly resulting in 500 error for all apps/Rmds

[FJCC]

Updating packages seems to have fixed a similar problem.

Shiny not working, attempt to apply non-function

I'm trying to get Shiny to work, but even the built-in examples do not work. They only open a browser page with "An error occurred, attempt to apply a non-function". How can I fix this? See attached screenshot with session info. [afbeelding] I also tried a basic Hello World example copy-pasted from a tutorial, with in "app.R" the following code: ui <- fluidPage("Hello, world!") server <- function(input, output, session) {} shinyApp(ui, server) This has the same result, with a slightly different error message in RGui: Warning: Error in mfunc: attempt to apply non-function 1: shiny::runApp