Hi 9872,
Thanks for posting in Apple Support Communities! The next step would be to check for an update. Outdated software can cause features to misbehave. These steps should help:
- "Back up your device using iCloud or your computer.
- Plug your device into power and connect to the internet with Wi-Fi.
- Go to Settings > General, then tap Software Update.
- If you see more than one software update option available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now."
-Update your iPhone or iPad
Updating your software may allow you to send voice messages again. If you're following the steps to send voice messages from the article Send and receive messages on iPhone, and you continue to receive this error after updating, contact Apple Support for further assistance.
Cheers!