Answer: Confirm the endpoint
type matches the file (IMAGE vs REEL/VIDEO), re-encode to a common MP4/H.264 or standard image format, and ensure the URL returns the real file (not an HTML login page).What this means in a real publishing workflow
A file extension does not prove the media encoding is supported. Providers inspect the container, codecs, pixel format, dimensions, duration, audio stream, and sometimes metadata placement.
Recommended implementation
- Inspect the file with ffprobe or an equivalent media analyzer.
- For broad video compatibility, use MP4 with H.264 video and AAC audio.
- Use yuv420p, even dimensions, and faststart metadata.
- Re-encode once, verify the output, and retry the failed destination only.
How to verify the fix
Images should return a real image Content-Type and use a platform-supported format. A URL returning HTML with a .jpg or .mp4 name is still invalid media.
Operational check: Test with one item, confirm the final destination and Postifys history state, and only then enable the recurring workflow. Keep the returned Postifys ID beside the source row so every result remains traceable.
Related Postifys resources
API documentation · Error reference · n8n automation guide · Safe retry guide · Compatibility matrix