X API v2 media upload endpoints launch, with dedicated chunked upload

What changed

X launched media upload endpoints in X API v2 on January 16, 2025. On April 30, 2025 the changelog added dedicated endpoints for chunked media upload and mentions an extended migration deadline, but the entry itself does not state the date. By September 2026 the chunked upload quickstart uses POST /2/media/upload/initialize, then /{id}/append and /{id}/finalize.

What it means

Image and video uploads for scheduled posts have a v2 path, and later chunked upload uses dedicated v2 endpoints.

Who is affected

Developers of scheduling tools that attach images or video to X posts.

What to do

Build or move media upload to the v2 endpoints. For large files use the chunked flow (initialize, append, finalize). The changelog states no deadline for retiring the older upload flow, so check the forum post it links for the migration deadline.