Invites are bound to the address they were sent to, which is what stops a forwarded link from becoming an open door into your workspace.
Signed in with the wrong address
This invite was sent to name@company.com - sign in with that email to accept.
The most common case by far. Sign out, then sign in or register with exactly the address in the message. If that address has no account yet, register it first: the invite waits.
The link is invalid or revoked
This invite link is invalid or was revoked.
Invite required
Either the owner revoked it, or the URL was broken across lines by a mail client. Ask the owner to send a new invite, and click the link in the mail rather than pasting it.
Already invited or already a member
That email is already invited or a member.
Nothing to do. Check the member list in Profile then Workspace: if the row says Pending, the original invite is still live and re-sending is unnecessary. Revoke and re-invite only if the original mail is genuinely gone.
Inviting yourself
That's you - you already have the owner seat.
The owner is already in the workspace and does not consume an invite.
Not found
Member not found.
The membership row was already removed, usually because two people acted on the same list at once. Refresh the page.
When in doubt, the workspace member list is the source of truth: it shows every active member and every pending invite with the date it was sent.