On WeBWorK-2.14 the server certificate was updated after which we noticed this error that the Library Browser does not let us choose a target set, or add problems to the target set.
The error message is
500 Can't connect to webwork.utrgv.edu:443 (SSL connect attempt failed error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol) at /app/webwork/webwork2/lib/WebworkClient.pm line 293.
Later: Error messages
xmlrpcCall to listSetProblems returned no result for
Old Library browser works ($showeditors{librarybrowsernojs} = 1;)
Strangely, now even if we reinstall the old certificate still we get the same error. Supposedly nothing was changed on the sever. I don't know about the university firewall.
I see a possibly related post with no resolution other than using the old Library Browser https://webwork.maa.org/moodle/mod/forum/discuss.php?d=4164
instructorXMLHandler is also throwing similar error message.