It’s time again for us to wind down certain versions of SNORT. We currently support 36 different OS builds for the Snort Subscriber Rule Set. Each additional version of OS and Snort that we have to support exponentially increases the amount of build and QA time required to create a version of the ruleset. The following versions of Snort will deprecate on Dec. 18 later this year. We recommend you upgrade to 2.9.0 or 29.12.0 immediately.”]
Source: https://blog.snort.org/2019/09/snort-versions-eol-and-open-source.html