Googlebot Crawl Errors

I received a message from Google that says,

“Googlebot has identified that an increased number of URLs on https://nysbs.org/ return a server error HTTP 5xx. As a result, users might not be able to see your content at all, and Google might not be able to index and show your pages in search results.” It gave the link to view the crawl errors, and every one of them (177 in all) are .php files associated with the Ai1C calendar plug-in. I have not updated the calendar to the most recent version yet because of the errors I’ve read that others are encountering when doing so. Is there any solution to this?