R: error with ggplot2 in loading ggraph

Question

I'd like to use ggraph package , but loading it, I got this error:

library(ggraph)
Error: package or namespace load failed for ‘ggraph’:
 object ‘scale_type’ is not exported by 'namespace:ggplot2'

What does it mean? How can I fix it? I'm not finding any answer on the Internet. Thanks in advance.
I am running on Windows 10 this version of R:

    > shortRversion()
[1] "R-3.5.1_2018-07-02"

Answer 1

I was able to fix this specific error by reinstalling the latest ggplot2 version.

remove.packages("ggplot2")
install.packages("ggplot2")

It seems that ggraph depends on this current version of ggplot2 .