This blog is updated daily.
A general description is here.
The non-API header ‘R_ext/R-ftp-http.h’ is no longer provided. The entry points it included are either deprecated or defunct.
Facilities for accessing ‘ftp://’ sites are no longer tested (except _pro tem_ for ‘curlGetHeaders()’) as browsers are increasing removing support.
On Windows, ‘download.file(method = "auto")’ uses ‘"libcurl"’ for ‘ftp://’ sites provided R was built with ‘libcurl’ support.
‘matrix(x, n, m)’ now warns in more cases where ‘length(x)’ differs from than ‘n * m’; suggested by Abby Spurdle and Wolfgang Huber in Feb 2021 on the R-devel mailing list.
This warning can be turned into an error by setting environment variable ‘_R_CHECK_MATRIX_DATA_’ to ‘TRUE’: ‘R CMD check --as-cran’ does so unless it is already set.
The (non-default) ‘method = "internal"’ for ‘download.file’ and ‘url’ no longer supports ‘ftp://’ URIs.
Similarly on Windows for ‘download.file(method = "wininet")’.