I cannot really tell from the info you provide what the problem ist. What is the difference between the platforms you run the stuff on, like - different versions of perl, IO::Socket::SSL, openssl, Net::SSLeay installed - the certificates you use differ - the certificates reside in other directories or you start the script in other directories (so that it cannot find the certificate) And then, Version 1.08 is quiet old (about 2 years) and in the meantime there were lots of bugfixes and added features.