"Cannot Send Message -- iMessage needs to be enabled to send this message."

Why do I keep getting an error when I try to send lots of photos and a video to an Android user, even though my iMessage is working fine? If I send just a few photos, it’s okay. I have an old iPhone 4S with both 3G data and fast wifi turned on. Both me and the person I’m sending to are on Verizon Wireless. I even tried turning iMessage off and on again, but it didn’t help.

To send this message, make sure iMessage is turned on. This might happen after you update your iPhone or iPad when settings change. You can fix it easily by turning Airplane mode on and off, force-quitting Messages, or restarting your iPhone or iPad.