I've recently migrated my MacBook to Catalina and I think that this has caused httr::GET calls to fail with the message:
Error in curl::curl_fetch_memory(url, handle = handle) :
Failed sending HTTP request
I've added in my Security & Privacy settings for R and Studio but that's not helped
POSTSCRIPT: I got this working - I think that httr's add_headers is less forgiving of sloppy coding than before
I hope that someone else has had the same problem and knows how to resolve this