Error while getting certificate from staging environment

[artemla]

Hello. I'm trying to test the newly installed script. If I set the option "Do you want to issue real SSL certificate (LIVE)?" to "No" and press "Issue Free SSL", I'm getting the next error:

Array
(
    [type] => urn:ietf:params:acme:error:malformed
    [detail] => Method not allowed
    [status] => 405
)

But, if I'm trying to get real certificate - all works as expected. It seems some changes in protocol, according to this post.