An Image Preview Works but Its Shared Link Fails? Check for a Temporary blob: URL

An image previews locally, but its copied address fails on another device or in a published article. Check whether it starts with blob:. A website origin appearing inside that string does not prove the image was uploaded to the site's server.

A temporary reference is not proof of storage

The MDN blob-URL guide describes an opaque identifier associated with an in-memory resource and managed with createObjectURL and revokeObjectURL. It can support previews and downloads, but depends on the backing object and creating environment rather than providing an arbitrary device with a permanent public image.

Browsers release associated object URLs when the document unloads. Explicit revocation and storage-partition restrictions can also matter. For persistent delivery, retain the actual file or use the existing storage flow to obtain an independently usable URL instead of copying only a temporary string.

Check three different deliverables

1. The current preview reference: is it an object URL or an actual HTTP resource?
2. The file: can it be saved and reopened with the intended dimensions, encoding and appearance?
3. The published reference: can the intended environment access a resource that was actually persisted?

A cover preview succeeding on its author's machine answers only part of that chain. Placing a blob URL in published content, a cover field or a sitemap does not upload its underlying bytes.

Do not revoke while the user still needs the resource

The revokeObjectURL reference concerns releasing an object URL no longer needed. MDN also warns that revoking immediately after an image renders can break later actions such as right-click saving or opening it in another tab. Let the actual component manage release when the resource is no longer available to the user.

Conversely, repeatedly creating object URLs without releasing them retains resources. Neither never releasing them nor waiting a magic number of milliseconds is a universal browser strategy. Accept the real preview, download and navigation lifecycle.

A hosted URL needs separate checks

With an HTTP image address, still verify status, actual content, MIME and permissions. A later Canvas SecurityError belongs to the separate cross-origin canvas checklist, rather than being merged with an expired object reference.

After preparing a delivery copy through the Resource Compression tool's normal file workflow, retain the downloaded file and validate its receiving environment. No Tooliva-internal object-URL implementation or browser lifecycle experiment is claimed. The artwork illustrates image data only.