Trace the asset URL
Open the failing asset request and note its status code and exact path. A 404 suggests a missing file or wrong URL; a blocked request or unexpected content type points to a different issue.
Check whether paths are relative to the current page or rooted at the site origin. Nested routes can make relative asset paths resolve under the wrong directory, while a configured base path may need to be included consistently.
Verify the build output and naming
Confirm that the source asset is included in the production build and that filename casing matches exactly. Some environments treat uppercase and lowercase names as distinct even when a development machine does not.
After fixing the path or build configuration, deploy again and test the public URL directly, including a nested page and a fresh browser session. Avoid masking missing files with a generic fallback that returns the page HTML for an asset request.