E15051 — WhatsAppGroupJoinRequestNotFound

One of the named join requests is not waiting for a decision on this group.

List the group's join requests and use the ids it returns. A request leaves the list once it is decided, and also when the person cancels it, so an id that was valid earlier can be gone by the time you use it. Only a group created with join_approval_mode approval_required collects join requests at all.