The R 3.5.0 update introduced a bug, at least under MS-Windows. File paths containing spaces are truncated at the first space character, leading to errors like:
Fatal error: cannot open file 'C:\Users\<user-name>\AppData\Roaming\WinEdt': No such file or directory
for a file path like
'C:\\Users\\<user-name>\\AppData\\Roaming\\WinEdt Team\\WinEdt 10\\<file-name>' or
'C:/Users/<user-name>/AppData/Roaming/WinEdt Team/WinEdt 10/<file-name>'.
This bug breaks, among other things, the ‘RManager’ extension of the editor WinEdt. I would expect this to cause various other surprising errors after upgrading to R 3.5.0.
This bug is already corrected in the patched version of R 3.5.0 available through CRAN. For Windows, the most recent patched R version can be downloaded from https://cran.r-project.org/bin/windows/base/rpatched.html and installed as usual.