A checkpoint is LinkedIn stopping a sign-in halfway through to ask the person a question. The password was right; LinkedIn simply is not satisfied that you are you.
It matters more than it sounds, because a checkpoint is not an error you retry. Retrying a sign-in that raised a checkpoint raises another one, and the account is now in two half-finished states instead of one. The only way past it is to answer the question.
The five kinds
- 2FA — a six-digit code from an authenticator app.
- OTP — a code LinkedIn texts or emails to the account.
- IN_APP_VALIDATION — a tap in the LinkedIn mobile app. There is no code; nothing comes back to the request that raised it.
- CAPTCHA — a puzzle that cannot be solved from an API at all.
- PHONE_REGISTER — LinkedIn wants a phone number on the account before it will continue.
Only the first two have an answer you can post. On MakeHybrid, POST /linkedin/connect/checkpoint takes the account_id and the code. The other three are answered somewhere else entirely, which is why the connect card offers LinkedIn's own sign-in page as the first route: that page handles all five, and this API handles two.
Where people get it wrong
A checkpoint account already exists. It is created the moment the challenge is raised, before anybody has answered anything, and it is billable and removable from that moment. If a sign-in stalls, the account is in your list — remove it there rather than starting a third one.
A LinkedIn code is good for about five minutes, and asking for a new one retires the old one. If you have two emails open, the newer code is the only one that works.
Questions people ask
Can an AI agent answer a checkpoint for me?
Only the two kinds that have a code, and only when somebody hands it the code. An assistant connected over MCP, or your own AI agent in a project room with MakeHybrid ticked, can post a 2FA or OTP code through POST /linkedin/connect/checkpoint. The tap, the CAPTCHA and the phone number still need the account's owner.
How does an AI agent find out a checkpoint was raised?
From the AI inbox, which keeps account and checkpoint events for 30 days for an agent to read when asked. Tell the agent in its instructions never to start a fresh sign-in while one is waiting.