Fatal error: Class CI_Session_files_driver contains 1 abstract method and must there

I seem to be experiencing this issue w/ opcache disabled on a recent macOS (Sierra 10.12.6) Homebrew install of PHP Version 7.1.10 running on Apache 2.4 mod_php that has CodeIgniter (3.1.4) intermittently (but quite often) throwing this same "PHP Fatal error: Class CI_Session_files_driver contains 1 abstract method ..."

I'll look into the helpful suggestion to use a different PHP SAPI like FPM as a solution, but thought it might be useful to indicate a non-Windows instance of this problem.