Shiny Apps not loading on R Version 4.1.0

I am falling at the first hurdle when attempting to create a dashboard with shiny.
As the most basic example...if I got to new --> shiny web app... and try to run the template code that appears (copied below), it doesn't work. I get 'Loading required package: shiny' in the console but I believe it should also say 'listening on [url]' which it doesn't.

All in all, nothing happens! Except that something is running and the only way I can get out of it is quit R.

I posted my session/version info at the very bottom.

Any help would be really appreciated!

This is a Shiny web application. You can run the application by clicking

the 'Run App' button above.

Find out more about building applications with Shiny here:

http://shiny.rstudio.com/

library(shiny)

Define UI for application that draws a histogram

ui <- fluidPage(

# Application title
titlePanel("Old Faithful Geyser Data"),

# Sidebar with a slider input for number of bins 
sidebarLayout(
    sidebarPanel(
        sliderInput("bins",
                    "Number of bins:",
                    min = 1,
                    max = 50,
                    value = 30)
    ),

    # Show a plot of the generated distribution
    mainPanel(
       plotOutput("distPlot")
    )
)

)

Define server logic required to draw a histogram

server <- function(input, output) {

output$distPlot <- renderPlot({
    # generate bins based on input$bins from ui.R
    x    <- faithful[, 2]
    bins <- seq(min(x), max(x), length.out = input$bins + 1)

    # draw the histogram with the specified number of bins
    hist(x, breaks = bins, col = 'darkgray', border = 'white')
})

}

Run the application

shinyApp(ui = ui, server = server)


This is my session/version info:
Show in New Window
R version 4.1.0 (2021-05-18)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19041)

Matrix products: default

locale:
[1] LC_COLLATE=English_United Kingdom.1252 LC_CTYPE=English_United Kingdom.1252 LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats graphics grDevices utils datasets methods base

loaded via a namespace (and not attached):
[1] compiler_4.1.0 htmltools_0.5.1.1 tools_4.1.0 yaml_2.2.1 rmarkdown_2.8 knitr_1.33 xfun_0.23
[8] digest_0.6.27 rlang_0.4.11 evaluate_0.14
_
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 4
minor 1.0
year 2021
month 05
day 18
svn rev 80317
language R
version.string R version 4.1.0 (2021-05-18)
nickname Camp Pontanezen

FWIW, I copied your code, saved it as app.R, commented out the non-code lines, and it worked correctly for me.

When looking at my session info output, I have shiny_1.6.0 listed under "other attached packages:" which I don't see in your output.

Hey,

Thanks for responding. I have shiny v 1.6.0 as well.

I tried running even the most basic shiny example in the console:

library(shiny)
runExample("01_hello")

this works for my peers, but not for me!!

They get the dashboard popping up and I get....nothing...

I'm definitely outside my comfort/knowledge zone here, but it seems others (maybe) have reported similar issues with 4.1 and so I wonder if you might try to test this in 4.05 and see if the issue persists?

Thank you!!!! So so much! I downloaded version 4.0.5 (I had 4.1.0 before) and by reverting to the older version, it worked perfectly.
So it looks like shiny apps don't launch in RStudio with R version 4.1.0. I'm on windows, maybe it works on other OS?!
Anyway, thanks so much, really appreciate your help.

Generally, is there a way to let the people who make Shiny know about this? I'm thinking it would be helpful to highlight it and save others the stress.

1 Like

Glad to hear! And yes, a little worrisome. I'm running 4.05 so won't update.

Maybe you could change the title of your post to "Shiny not running on R4.1.0" or similar and hope someone sees it?

1 Like

Yes I will do this :slight_smile: good idea

Works for me on latest versions

I'm having this exact same issue. I can't run shiny apps using R version 4.1.0 from RStudio version 1.4.1717, but my apps run fine if I revert to R version 4.0.5.