问题：
pyinstaller 打包后，运行生成的exe报错 “recursion is detected during loading of “cv2“ binary extensions.”
Traceback (most recent call last):
File "Sy.py", line 15, in <module>
File "PyInstaller\loader\pyimod03_importers.py", line 495, in exec_module
File "cv2\__init__.py", line 180, in <module>
bootstrap()
File "cv2\__init__.py", line 152, in bootstrap
native_module = importlib.import_module("cv2")
File "importlib\__init__.py", line 126, in import_module
File "PyInstaller\loader\pyimod03_importers.py", line 495, in exec_module
File "cv2\__init__.py", line 180, in <module>
bootstrap()
File "cv2\__init__.py", line 75, in bootstrap
raise ImportError('ERROR: recursion is detected during loading of "cv2" binary extensions. Check OpenCV installation.')
ImportError: ERROR: recursion is detected during loading of "cv2" binary extensions. Check OpenCV installation.
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使用pip卸载opencv，pip uninstall opencv*******(具体的安装的opencv的名字)
到%:\python\Lib\site-packages%路径（安装的python的路径）下删除cv2的文件夹
再用pip重新安装opencv，pip install opencv****
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解决方法（可依次尝试）：
1.重装cv2。（这是回答比较多的，多数情况有用）
先pip unintall opencv-python ，再pip intall opencv-python
2.设置环境变量。
参考：
Python-Opencv [ERROR: recursion is detected during loading of "cv2"_凌空的桨
3.降低cv2版本。
pyinstaller和cv2的版本存在兼容问题。本人用的pyinstaller是4.7(python3.8.0)，cv2是4.5.4.58，结果出错，把cv2版本降低到4.5.1.48再打包，就不报错了。
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https://wiki.archlinux.org/index.php/Arch_Linux_Archive#How_to_downgrade_one_package
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open cmd and use pip to install a different version:
pip install opencv-python==4.5.3.56========================
opencv-python 4.5.5.62
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