RStudio server autocomplete generates errors about .Internal

I am using RStudio server. RStudio version 1.1.463. R version 3.6.0.

When typing code, whenever autocomplete would suggest something, one of the following errors appears in console instead:

Error in print.default(item$value) : 9 arguments passed to .Internal(print.default) which requires 3
Error in print.default(functionCall[[1]]) : 9 arguments passed to .Internal(print.default) which requires 3
Error in .Internal(print.function(x, useSource, ...)) : there is no .Internal function 'print.function'

(The numbers in the first two messages are always 9 and 3.)

Often, a pop-up error message "R code execution error" pops up together with the console message.

Any help is appreciated.

The support article Startup error in RStudio IDE - "7 arguments passed to .Internal()" is relevent here.

This is most likely due to a conflict in R version, possibly caused by .Rprofile or .Renviron. The support article provides suggestions for remedies.