Thank you for your answer joels,
I found a prior post related with this issue.
I'm using RStudio version 1.2.5033
When I go to Tools / Global Options / Publishing RStudio asks for publishing accounts in ShinyApps.io
or in RStudio Connect.
The option for RPubs is no longer available.
As you tell me that you were perfectly able to publish recently an Rmarkdown report, I do not know what I'm doing wrong
Thank you for your help