Hello Iris,

Tia from the Support Team here to help .

When you connect a Whatsapp channel, you are routed to Facebook.com to complete the integration process. The error you are seeing is occurring within this part workflow and coming from them directly. 

We recommend reaching out to Meta Support for further investigation. 

If you have any additional questions , please feel free to reach out to us at Support@Frontapp.com

Best,
Tia Dennington
Customer Support Representative