title: Error parsing text-format opencv_tensorflow.GraphDef
body: <p>I want to use the function <code>cv2.dnn.readNetFromTensorflow</code> giving as parameters .pb and .pbtxt files in order to make predictions from a model trained in python but I get this error:</p>
  <pre><code>Error parsing text-format opencv_tensorflow.GraphDef: 18749:5: Unknown enumeration value of &quot;DT_VARIANT&quot; for field &quot;type&quot;. 
  </code></pre>
  <p>I tried different tf versions but the error is still present, did I create a wrong .pbtxt file?</p>