How to solve WhatsApp “Couldn’t link device” error?

Problem
When using Link as a companion device, WhatsApp may show:

“Couldn’t link device”
or
“Something went wrong. Please try again.”

What to check

1. WhatsApp allows up to 4 additional linked devices. Remove an old linked device if the limit has been reached.
2. Check WhatsApp > Linked devices and remove any device that is no longer needed.
3. Try linking again after restarting WhatsApp.
4. If the issue continues, use WhatsApp Web as a temporary option.

Note: WhatsApp Web may not provide the same notification experience as the app.