iMessage not working
Every time I turn on iMessage is says IMessage Activation An error occurred during activation Try again.
Messages - If you get an error when trying to activate iMessage or FaceTime.
Some things you can try. Do you have access to another WiFi network where you can try? That has worked for several people.
Try a restart.
Restart your iPhone, iPad, or iPod touch
Try a forced restart.
If necessary
Do a backup and try a factory reset. Then restore from your backup.
Restore - If you see an error when you update or restore your iPhone, iPad, or iPod
Backup - Restore your device from an iCloud or iTunes backup.