Shiny: Browser Call Inside Observe Causes gregexpr Error

[DarioS]

Using browser() inside an observer to do debugging causes an error in recent versions of Shiny. It worked without a problem in versions 0.12.2 or older. The error is Error in gregexpr(calltext, singleline, fixed = TRUE) : regular expression is invalid UTF-8

library(shiny)

ui <- fluidPage(
 selectInput(inputId = "choice", "Choices", LETTERS[1:2])
 )
 server <- function(input, output, session) {
 observe({
 input[["choice"]]
 browser()  # Doesn't error if this line is commented.
 })
 }

shinyApp(ui = ui, server = server)

[bborgesr]

Hmm, I don't get this... Try starting with a clean working environment and re-installing? Or tell me how I can repro it...

> library(shiny)
> 
> ui <- fluidPage(
+     selectInput(inputId = "choice", "Choices", LETTERS[1:2])
+ )
> server <- function(input, output, session) {
+     observe({
+         input[["choice"]]
+         browser()  # Doesn't error if this line is commented.
+     })
+ }
> 
> shinyApp(ui = ui, server = server)

Listening on http://127.0.0.1:3607
Called from: observerFunc()
Browse[1]> n
Called from: observerFunc()
Browse[1]> n
Called from: observerFunc()
Browse[1]> n
Called from: observerFunc()
Browse[1]> 

> devtools::session_info("shiny")
Session info ----------------------------------------------------------
 setting  value                       
 version  R version 3.3.0 (2016-05-03)
 system   x86_64, darwin13.4.0        
 ui       RStudio (1.0.125)           
 language (EN)                        
 collate  en_US.UTF-8                 
 tz       Europe/Lisbon               
 date     2016-11-20                  

Packages --------------------------------------------------------------
 package     * version  date       source                        
 digest        0.6.10   2016-08-02 cran (@0.6.10)                
 htmltools     0.3.5    2016-03-21 CRAN (R 3.3.0)                
 httpuv        1.3.3    2015-08-04 CRAN (R 3.3.0)                
 jsonlite      1.1      2016-09-14 CRAN (R 3.3.0)                
 mime          0.5      2016-07-07 CRAN (R 3.3.0)                
 R6            2.2.0    2016-10-05 cran (@2.2.0)                 
 Rcpp          0.12.7.5 2016-11-07 Github (RcppCore/Rcpp@88ebc36)
 shiny       * 0.14.2   2016-11-01 CRAN (R 3.3.0)                
 sourcetools   0.1.5    2016-09-15 CRAN (R 3.3.0)                
 xtable        1.8-2    2016-02-05 CRAN (R 3.3.0)   

[DarioS]

I found out that this only happens if the application is run in RStudio on Windows. If I run the example using RGui in Windows instead, it doesn't happen. Also, it doesn't happen if the application is run in RStudio but in a Debian operating system.

How should I report this? There's no public issue tracker for RStudio. I am using version 1.0.44, currently the newest released version of the IDE.

[kevinushey]

RStudio IDE team member here -- I've reproduced this and logged a bug on the RStudio side for us to take a look. Thanks for reporting!

[bborgesr]

Thanks both!

[ayguno]

I still reproduce this in my own code within an observer in Shiny as of today.

[havukkala]

Same error message for me still today.

[stevenmosher]

Same Issue for me today.

Everything was working fine. No issues and then BAM. this error.

Error in gregexpr(calltext, singleline, fixed = TRUE) :
regular expression is invalid UTF-8

[DomenFinzgar]

Exactly the same problem!

the solution was to "Reopen with Encoding ..."

[DarioS]

RStudio takes at least a year to fix most bugs. They're grossly understaffed.

[kevinushey]

@DarioS: for what it's worth, this issue appears to be resolved in R 3.4.1 (at least, I wasn't able to reproduce on my Windows VM when running with the 64bit version of R 3.4.1). Nonetheless, we're still tracking this issue for the v1.1 release of RStudio and hope to have it fixed there as well.

[YsoSirius]

Although the error isnt really harmful, I am still getting it with R 3.5.2 and RStudio 1.1.463

Browse[1]> c
Error in gregexpr(calltext, singleline, fixed = TRUE) : 
  regular expression is invalid UTF-8
Error in gregexpr(calltext, singleline, fixed = TRUE) : 
  regular expression is invalid UTF-8

[fgoerlich]

I am still getting the same error, even not always, with R 3.6.1 and RStudio 1.2.5001

Error in chartr("ŠŽšžŸÃ\200Ã\201ÂÃÄÅÇÃ\210ÉÊËÌÃ\215ÃŽÃ\217Ã\220ÑÒÓÔÕÖÃ\231ÚÛÜÃ\235à áâãäåçèéêëìíîïðñòóôõöùúûüýÿ", :
'old' is longer than 'new'
Called from: chartr("ŠŽšžŸÃ\200Ã\201ÂÃÄÅÇÃ\210ÉÊËÌÃ\215ÃŽÃ\217Ã\220ÑÒÓÔÕÖÃ\231ÚÛÜÃ\235à áâãäåçèéêëìíîïðñòóôõöùúûüýÿ",
"SZszYAAAAAACEEEEIIIIDNOOOOOUUUUYaaaaaaceeeeiiiidnooooouuuuyy",
string)
Error during wrapup: regular expression is invalid UTF-8