Fantastical 3 requires watchOS 6 to run. Apple Watch Series 1 and later are capable of running watchOS 6 but Apple Watch Series 0 can't, and therefore is not compatible with Fantastical 3.
It takes a few minutes for your iPhone to transfer the updated app to your Apple Watch after updating. Wait 5-10 minutes before trying to use Fantastical on your Apple Watch after updating. If Fantastical still doesn't open after waiting 5-10 minutes, restart your Apple Watch and try again.
Apple Watch only allows a small amount of data to be sent from your iPhone to your watch. Because of this, Fantastical on Apple Watch may not be able to show events too far into the future and instead keeps you informed of events that are more likely to be relevant to you.
If you are having trouble with Fantastical's complication not updating, please try refreshing Fantastical on your Watch:
If this doesn’t help, sign out of your Flexibits account and back in again:
If this doesn’t help either, please remove Fantastical from your Watch and add it back again:
This likely means you are not logged in to your Flexibits account on your iPhone. Please open Fantastical on your iPhone and go to Settings > Flexibits Account and sign in. If you don’t already have a Flexibits account, please create one as we require this for your Apple Watch to sync with your iPhone.
Fantastical 3 requires a free Flexibits account to sync between Fantastical on iPhone and Apple Watch. This allows the Apple Watch app to update even when it's not near your iPhone. For example, you'll still be able to add events and complete tasks even if you leave your phone at home but are connected to a remote Wi-Fi network or have a cellular Apple Watch.
All data sent between your iPhone and Apple Watch is end-to-end encrypted, which means your data is kept private while syncing.
Flexibits can’t read your calendar data. Event and task data synced to your Apple Watch is sent through Flexibits' servers, but this data is end-to-end encrypted and thus we are unable to read it. Please refer to our privacy page for detailed information concerning how we manage your data: https://flexibits.com/privacy