Today I was able to download and install the next version (4.6) of the R programming language. Almost exactly a year ago I posted about retaining libraries during an R upgrade. So I followed my own advice (not always a good idea but appropriate in this case), copied the version 4.5 user packages over to 4.6, and then checked for any needing an update. The only one flagged in my case was the devtools package ... but when I tried to update it, the update failed.
The initial error message pointed to a missing symbol definition in the rlang package. There was no update available for rlang, so I uninstalled it, reinstalled it (no glitches) and then tried devtools again. This time, I got a missing symbol error relating to a different package (vctrs). Encouraged by the fact that it at least was not complaining about rlang anymore, I uninstalled and reinstalled vctrs, then ran the devtools update yet again. This time the update succeeded.
I'm not sure I took the most efficient path here, but at least I made it to the goal line.
