To solve the "Necessary Checkpoint" error, you should follow the instructions bellow:
- Logout and login your Instagram account;
- Check if the Instagram have sent to you any account verification. If yes, click in "Yes, It was me";
- Do some manual action on your account (like, follow and unfollow).
Then, you should wait for a few minutes and check if your account reverts back to usual activity.
For any other assistance please send a ticket to the support team.