When sending messages to multiple recipients from Kriyo, WhatsApp may show an error because WhatsApp does not allow sending a single message to multiple phone numbers at once from the device’s share or messaging interface.
When multiple recipients are selected, WhatsApp treats all the selected numbers as one combined number, which results in an error such as “This number is not registered on WhatsApp.” This happens even if each individual recipient is actually on WhatsApp.
If you select only one recipient, WhatsApp will work as expected and allow you to send the message. For sending messages to multiple recipients at the same time, using the SMS option ensures reliable delivery.