The "hsts" option isn't allowed to be nested within a "location" option. See parse.y:572.
Index: httpd.conf.5 =================================================================== RCS file: /cvs/src/usr.sbin/httpd/httpd.conf.5,v retrieving revision 1.68 diff -u -p -r1.68 httpd.conf.5 --- httpd.conf.5 19 Jul 2015 05:17:27 -0000 1.68 +++ httpd.conf.5 14 Apr 2016 03:27:58 -0000 @@ -300,6 +300,7 @@ argument will be matched against the req A location section may include most of the server configuration rules except .Ic connection , +.Ic hsts , .Ic listen on , .Ic location and
