syncthing/gui/default/syncthing/core/upgradingDialogView.html

<modal id="upgrading" status="info" icon="arrow-circle-up" heading="{{'Upgrading' | translate}}" large="no" closeable="no">
  <div class="modal-body">
    <p>
      <span translate>Syncthing is upgrading.</span>
      <span translate>Please wait</span>...
    </p>
  </div>
</modal>