In almost every case the fix is the same: ask the person who invited you to resend the invitation from Settings → Team → Pending. A resend gives you a fresh link that is valid for 7 days. The page you land on tells you which of the cases below applies.
The page says the invitation has expired
The page says the invitation has expired
Invitation links are valid for 7 days from the last time the invitation was sent. Ask an Owner, Admin or Manager of the workspace to resend it. They do not need to remove and re-invite you.
The page says the link is not recognized
The page says the link is not recognized
The link was probably cut off or changed by your email app, or the invitation was revoked. Open the email again and select the button rather than copying the address. If that fails, ask for a new invitation.
The page says the link was already used
The page says the link was already used
Each invitation works once. If you already joined, sign in to Samba and you will find the workspace there. If you are signed in under a different email address than the one that was invited, ask for an invitation to the address you want to use.
I see a "wrong account" page
I see a "wrong account" page
You are signed in to Samba with a different email than the one that was invited. The page names both addresses. Choose to sign out and continue as the invited address, or ask for an invitation to the account you are signed in with.
I accepted, but I still cannot open the workspace
I accepted, but I still cannot open the workspace
Until a workspace is activated, only its owner can open it. You will get in as soon as the owner puts a card on file. See Set up your workspace.
I never received the email
I never received the email
Check your spam folder, then ask the person who invited you to confirm the address and resend. They can resend once every 10 minutes. The email is always in English.