Python 2.7 is not supported anymore in opencv-python-4.3.0.38 the support was dropped since 4.3.0.36,
The workaround I found was to install opencv-python version 4.2.0.32 (which is the latest supported for Python 2.7, see this for all releases) like this:
pip2 install opencv-python==4.2.0.32
Hope this helps!!
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