Hello,
I have exactly the same problem than @mafose in this post. As the threat is already closed, but not answer posted, I start a new post.
Since a few days I get the error "Error listing packages" when I start RStudio and in the console the notification "Error in readRDS(pfile): cannot read workspace version 3 written by R 3.6.0; need R 3.5.0 or newer"
RStudio is running in windows on a citirx workspace.
Any idea?
Andreas