Question: PS C:\Users\Lenovo> pip install pickle5 Collecting pickle5 Using cached pickle5-0.0.11.tar.gz (132 kB) Preparing metadata (setup.py) ... done Using legacy 'setup.py install' for pickle5, since package 'wheel' is not installed. Installing collected packages: pickle5 Running setup.py install for pickle5 ... error error: subprocess-exited-with-error × Running setup.py install for pickle5 did not run successfully. │ exit code: 1 ╰─> [36 lines of output] running install running build running build_py creating build creating build\lib.win-amd64-3.10 creating build\lib.win-amd64-3.10\pickle5 copying pickle5\pickle.py -> build\lib.win-amd64-3.10\pickle5 copying pickle5\pickletools.py -> build\lib.win-amd64-3.10\pickle5 copying pickle5\__init__.py -> build\lib.win-amd64-3.10\pickle5 creating build\lib.win-amd64-3.10\pickle5\test copying pickle5\test\pickletester.py -> build\lib.win-amd64-3.10\pickle5\test copying pickle5\test\test_pickle.py -> build\lib.win-amd64-3.10\pickle5\test copying pickle5\test\test_picklebuffer.py -> build\lib.win-amd64-3.10\pickle5\test copying pickle5\test\__init__.py -> build\lib.win-amd64-3.10\pickle5\test running build_ext building 'pickle5._pickle' extension creating build\temp.win-amd64-3.10 creating build\temp.win-amd64-3.10\Release creating build\temp.win-amd64-3.10\Release\pickle5 C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -IC:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\include -IC:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\Include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\cppwinrt /Tcpickle5/_pickle.c /Fobuild\temp.win-amd64-3.10\Release\pickle5/_pickle.obj _pickle.c C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -IC:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\include -IC:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\Include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.22000.0\cppwinrt /Tcpickle5/picklebufobject.c /Fobuild\temp.win-amd64-3.10\Release\pickle5/picklebufobject.obj picklebufobject.c pickle5/picklebufobject.c(20): warning C4273: 'PyPickleBuffer_FromObject': inconsistent dll linkage C:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\include\cpython/picklebufobject.h(18): note: see previous definition of 'PyPickleBuffer_FromObject' pickle5/picklebufobject.c(39): warning C4273: 'PyPickleBuffer_GetBuffer': inconsistent dll linkage C:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\include\cpython/picklebufobject.h(22): note: see previous definition of 'PyPickleBuffer_GetBuffer' pickle5/picklebufobject.c(58): warning C4273: 'PyPickleBuffer_Release': inconsistent dll linkage C:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\include\cpython/picklebufobject.h(24): note: see previous definition of 'PyPickleBuffer_Release' pickle5/picklebufobject.c(208): warning C4273: 'PyPickleBuffer_Type': inconsistent dll linkage C:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\include\cpython/picklebufobject.h(13): note: see previous definition of 'PyPickleBuffer_Type' C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\bin\HostX86\x64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EMBED,ID=2 /MANIFESTUAC:NO /LIBPATH:C:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\libs /LIBPATH:C:\Users\Lenonvo\AppData\Local\Programs\Python\Python310\PCbuild\amd64 /LIBPATH:C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\lib\x64 /LIBPATH:C:\Program Files (x86)\Windows Kits\10\lib\10.0.22000.0\ucrt\x64 /LIBPATH:C:\Program Files (x86)\Windows Kits\10\lib\10.0.22000.0\um\x64 /EXPORT:PyInit__pickle build\temp.win-amd64-3.10\Release\pickle5/_pickle.obj build\temp.win-amd64-3.10\Release\pickle5/picklebufobject.obj /OUT:build\lib.win-amd64-3.10\pickle5\_pickle.cp310-win_amd64.pyd /IMPLIB:build\temp.win-amd64-3.10\Release\pickle5\_pickle.cp310-win_amd64.lib python310.lib(python310.dll) : error LNK2005: PyPickleBuffer_GetBuffer already defined in picklebufobject.obj Creating library build\temp.win-amd64-3.10\Release\pickle5\_pickle.cp310-win_amd64.lib and object build\temp.win-amd64-3.10\Release\pickle5\_pickle.cp310-win_amd64.exp build\lib.win-amd64-3.10\pickle5\_pickle.cp310-win_amd64.pyd : fatal error LNK1169: one or more multiply defined symbols found error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\BuildTools\\VC\\Tools\\MSVC\\14.29.30133\\bin\\HostX86\\x64\\link.exe' failed with exit code 1169 [end of output] note: This error originates from a subprocess, and is likely not a problem with pip. error: legacy-install-failure × Encountered error while trying to install package. ╰─> pickle5 note: This is an issue with the package mentioned above, not pip. hint: See above for output from the failure. 

Answer: You only need pickle5, a module backporting Pickle protocol 5 features to older Pythons when running on Python versions older than 3.8. As evident from Python310 and -3.10 in the output, you're on Python 3.10. You don't need pickle5. Thus, the answer to "what should you do", without us not knowing more details about your situation, is "not try to install pickle5".