Understand why browser-generated thumbnails may not appear and what fallback paths VidFlow AI can use.
Content reviewed: October 18, 2026.
How thumbnail capture works
Use a Start Frame stored on your site when possible. VidFlow can use that image as the thumbnail.
Fallbacks
- Local same-origin video when the video is stored in WordPress.
- VidFlow can load a frame from an accessible provider-hosted video.
- Reopen Video Library or the project to let VidFlow try creating the thumbnail again.
Common blockers
- Browser cannot decode the video.
- Provider URL expired.
- Proxy request blocked.
- Temporary file creation blocked.
- Image or video CORS issue.
- Server security rules block the proxy route.
Fix path
- Use a Start Frame where possible.
- Check that the source video still previews.
- Confirm server temp storage is writable.
- Reopen the video in the admin to retry thumbnail creation.
Thumbnail access
Check the thumbnail on the page where it is missing, then inspect blocked image or video requests. Recover the thumbnail from the existing video before considering a new generation.