Match the message you see:
"No space found with that code"
- The code was already used. Each invite code works once. When someone joins, the space gets a new code. Ask for the current one: it's on their Shared tab under Share invite code.
- This also affects email invites: they carry the code that was current when they were sent. If someone else joined first, ask for a new invite.
- Typo? Codes are 10 letters and numbers. They never contain easily confused characters like O and 0 or I and 1.
"This invite has expired" Personal invite links (the ones that let you take over a member's slot) last 7 days. Ask for a new one.
"This space is full (maximum 20 members)" The space has reached 20 members, counting offline members. Its owner needs to remove someone first.
"You're already in a shared space (maximum 1 per account for now)" On the free plan you can be in one space at a time. Leave your current space first (see How do I leave a shared space?).
"Couldn't check this invite" Usually a connection problem. The invite itself may be fine. Check your internet and try again in a moment.
The link opens the app store instead of NEXO: install NEXO, sign in, then tap the link again. If you tapped it before signing in, NEXO usually remembers it for you.