Error 100: Unsupported API version in Facebook Graph API

Goal

Confirm that requests to the Facebook Graph API that specify a version string older than the current minimum supported version trigger the documented error 100, and identify the internal component that performs the check.

Constraints

The request must include an explicit version parameter (e.g., v2.0) and a valid access token. The behavior should be consistent across all Graph API endpoints (queries, mutations, subscriptions) and independent of permission scopes.

Unresolved Questions

1. Which internal component of the Graph API is responsible for rejecting unsupported version strings?
2. Will Facebook eventually replace the explicit error with an automatic upgrade to the latest supported version, or will the error remain?
3. What is the most reliable way to programmatically discover the minimum supported version for a given Graph API deployment?