I spent a while building a service that publishes to Instagram on a schedule. Most of that time did not go into the interesting parts. It went into errors whose message points nowhere near the actual cause.
Here is the list I wish I had found on day one.
1. Publishing is two calls, and the first one publishes nothing
You do not post a photo. You create a media container, then you publish that container:
POST /{ig-user-id}/media -> returns a creation_id






