If Set featured image opens a generic insert-media dialog, uploading another file is unlikely to solve the problem. Check the code that selects the media flow, especially plugins that extend the editor's MediaUpload component.
The compatibility change to inspect
Gutenberg pull request 83439 stabilizes unstableFeaturedImageFlow as featuredImageFlow. Its notes explain that transitional callers pass both names because some extensions still inspect the old prop. This is a specific API compatibility change, not proof that every unusual media modal is caused by it.
Record the WordPress and Gutenberg builds, the extension versions and the exact entry point that opens the modal. Test with a staging copy and a small licensed image. Preserve the current featured image ID before making changes.
Compare the three entry points
Test the post editor's featured-image panel first. Then test the DataForm inspector if that experiment is present and enabled on your test build. Finally check the Site Editor's page Quick Edit interface when available. Record the action label, selected image and result after saving in each context.
Select: Correct media flow. Cancel: Original selection preserved. Replace: New ID survives save. Remove: Expected empty state persists. Explanatory checklist, not a customer test result.
If only one entry point fails, that narrows the caller or integration boundary. If every upload fails, move to the WordPress image upload error diagnostic before changing flow props.
Inspect the extension without guessing a replacement
Search the integration's source for both prop names and for its MediaUpload extension point. Identify whether it is a caller passing the prop or a wrapper reading it. Those roles need different changes. A wrapper that drops unknown props can break behavior even when the caller sends the correct value.
Build a compatibility matrix with your oldest supported runtime and the current test runtime. Mark which prop names each caller supplies and which the wrapper recognizes. Use the upstream implementation as the reference for the runtime being tested. Avoid removing compatibility support from an extension merely because the development build no longer needs it.
Test data persistence, not just button text
- Select an existing image and save the post.
- Reopen and confirm the same featured image remains selected.
- Replace it with a second test image and verify the public template uses that image.
- Cancel the modal after making an unsaved selection and confirm the original remains intact.
- Remove the featured image through the normal interface and verify the saved state.
Use synthetic content for these tests. Do not overwrite a real editorial image simply to exercise the remove path. Confirm attachment permissions with the site's normal editor role; administrator success alone can hide a permission problem.
Deployment evidence
Keep the smallest source diff, version matrix and before/after saved image IDs. Clear the affected editor asset cache through the normal deployment process and reload a clean session. If a generic dialog still appears, inspect the actual shipped JavaScript rather than assuming the build picked up the source change.
Ask HandL WP to isolate a media-editor issue with the failing entry point and extension name. That is more actionable than a screenshot of the Media Library alone.
Primary source: featured-image flow stabilization. The checks above are recommended tests, not evidence that any specific third-party plugin is defective.
References reviewed October 17, 2026. Examples are explanatory, not customer test results.