shinyapps.io deployment: Error building image

Found an answer to this in Scott's post here: https://forum.posit.co/t/shiny-app-fails-for-deploy-after-updating-all-packages-the-url-is-scottkbrown-shinyapps-io-gcstats/28842

The application has been deployed, but now the application has failed to start with the following message:

── Attaching packages ─────────────────────────────────────── tidyverse 1.2.1 ──
✔ ggplot2 3.1.1       ✔ purrr   0.3.2  
✔ tibble  2.1.1       ✔ dplyr   0.8.0.1
✔ tidyr   0.8.3       ✔ stringr 1.4.0  
✔ readr   1.3.1       ✔ forcats 0.4.0  
── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::filter() masks stats::filter()
✖ dplyr::lag()    masks stats::lag()

Attaching package: ‘DT’

The following objects are masked from ‘package:shiny’:

    dataTableOutput, renderDataTable

Error in value[[3L]](cond) : trying to use CRAN without setting a mirror
Calls: local ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>
Execution halted