Fixed

You’ll probably need to capture an instance of maps into a react ref

(defsc ImageUpload [this props {:keys [on-scan]}]
  {:ident (fn [] [:component/id ::ImageUpload])
   :query []
   :initial-state {}
   :route-segment ["image"]}
  (let [ref (react/createRef)]
    (comp/fragment
      (ui-button {:icon true :labelPosition "left"
                  :onClick (fn [] (.openImageDialog (.-current ref)))}
        (ui-icon {:name "upload"})
        "Select Image"))))

https://reactjs.org/docs/refs-and-the-dom.html

Thanks! It works