Greetings,
For the past 7 hours our tireless devs and betatesters have been testing our forthcoming release 2.2 and previous release 2.15 with BF2 1.5.
Unfortunately we've found BF2 1.5 is incompatible with 2.15*. Therefore, we do not recommend that FH2 servers are upgraded to BF2 1.5 at this time, and that FH2 servers and players should continue to use BF2 1.41 as before.
We will be fixing this issue for the forthcoming 2.2 release. We're relatively confident it can be fixed as some planes are unaffected.
* To expand: the dedicated server crashes when entering most of our aircraft. The fix will involve determining the common cause across all affected aircraft, and changing our aircraft to avoid tickling this newly introduced BF2 bug.