If you have any problem to connect with your facebook friends please follow the step bellow
Step 1 > Download Latest version of Facebook and then try to connect with your facebook
(link- Facebook Latest version for Android)
If still not working follow step 2
Step 2 > You can Delete current version of Hay Day and then Download Old version of Hay Day.
(link- Hay Day old Version) and save to your phone memory.
For Full steps Click Here
Gameplay Support for Facebook Connection