Error: Unable to establish connection with RStudio Server when executing 'console_input'

[cuppacuppa]

I recently updated rstudio-server to 2023.03.2+454 in my ubuntu 18.04 server, and I encountered following error.

> substr("ABC", 1, 2)
Error: Unable to establish connection with RStudio Server when executing 'console_input'

Here is my session info.

> sessionInfo()
R version 4.4.1 (2024-06-14)
Platform: x86_64-pc-linux-gnu
Running under: Ubuntu 18.04.6 LTS

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/openblas/libblas.so.3 
LAPACK: /usr/lib/x86_64-linux-gnu/libopenblasp-r0.2.20.so;  LAPACK version 3.7.1

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8       
 [4] LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C              
[10] LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

time zone: Asia/Seoul
tzcode source: system (glibc)

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

loaded via a namespace (and not attached):
[1] compiler_4.4.1 tools_4.4.1   

This error only occurred when I use substr function of base package. I don't know why this problem happened. How can I solve it?