Unfortunately this is a browser issue and we have no control over it. WebKit based browsers (like Chrome and Safari) render the <input type="file" /> tag differently, and apparently for some reason Chrome puts a default tooltip on it. Since RadUpload and RadAsyncUpload both use the <input type="file" /> tag internally, this issue is observed in them as well.
You can test this yourself. Just put a regular <input type="file" /> on the page and observe it's behavior in Chrome.
the Telerik team
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