A website reports that your image was uploaded successfully. You add a reference video, click Generate, and a provider says it cannot download the file. It is easy to assume the model is broken. But the failure may occur before generation begins.
Two uploads, two possible delivery paths
An image reference and a video reference may take different routes through an application. One might be sent directly to the model provider's storage. The other might be represented by a signed URL pointing back to a private server.
Both can be valid approaches, but signed URLs must remain accessible long enough for the remote service to retrieve them. A link that works for you in a logged-in browser may still fail for a machine without your session cookies.
Common accessibility problems
A remote fetch can fail because the URL expired, because it is blocked by authentication, because the hosting server blocks remote requests, or because it redirects to an unsupported destination. Separately, the file may be readable but encoded in a format the model does not accept.
These problems often produce different error messages. Keep the provider response rather than replacing it with a generic “Something went wrong.”
What developers should validate
Check that the media is a real video file, confirm its size and content type, and verify a provider-accessible upload mechanism. If the service offers its own storage endpoint, using it for inputs can reduce dependence on private site URLs.
Never expose a permanent public link to users' private photos as a quick workaround. Access control still matters.
What users can do
Try a supported MP4 with a conventional codec, keep the duration within limits and avoid a corrupted or partially downloaded source. If the same input works elsewhere, send the application support team the job ID and exact error.
A file existing on your website is not the same as a file being reachable by the model that needs to read it.
