Question: I'm trying to install eth-brownie using 'pipx install eth-brownie' but I get an error saying pip failed to build package: cytoolz Some possibly relevant errors from pip install: build\lib.win-amd64-3.10\cytoolz\functoolz.cp310-win_amd64.pyd : fatal error LNK1120: 1 unresolved externals 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 1120  I've had a look at the log file and it shows that it failed to build cytoolz. It also mentions "ALERT: Cython not installed. Building without Cython.". From my limited understanding Cytoolz is apart of Cython so i think the reason why the installation for eth-brownie failed is because it could not build cytoolz as it was trying to build it without Cython. The thing is I already have cython installed: C:\Users\alaiy>pip install cython Requirement already satisfied: cython in c:\python310\lib\site-packages (0.29.24)  Extract from the log file (I can paste the whole thing but its lengthy): Building wheels for collected packages: bitarray, cytoolz, lru-dict, parsimonious, psutil, pygments-lexer-solidity, varint, websockets, wrapt Building wheel for bitarray (setup.py): started Building wheel for bitarray (setup.py): finished with status 'done' Created wheel for bitarray: filename=bitarray-1.2.2-cp310-cp310-win_amd64.whl size=55783 sha256=d4ae97234d659ed9ff1f0c0201e82c7e321bd3f4e122f6c2caee225172e7bfb2 Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\1d\29\a8\5364620332cc833df35535f54074cf1e51f94d07d2a660bd6d Building wheel for cytoolz (setup.py): started Building wheel for cytoolz (setup.py): finished with status 'error' Running setup.py clean for cytoolz Building wheel for lru-dict (setup.py): started Building wheel for lru-dict (setup.py): finished with status 'done' Created wheel for lru-dict: filename=lru_dict-1.1.7-cp310-cp310-win_amd64.whl size=12674 sha256=6a7e7b2068eb8481650e0a2ae64c94223b3d2c018f163c5a0e7c1d442077450a Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\47\0a\dc\b156cb52954bbc1c31b4766ca3f0ed9eae9b218812bca89d7b Building wheel for parsimonious (setup.py): started Building wheel for parsimonious (setup.py): finished with status 'done' Created wheel for parsimonious: filename=parsimonious-0.8.1-py3-none-any.whl size=42724 sha256=f9235a9614af0f5204d6bb35b8bd30b9456eae3021b5c2a9904345ad7d07a49d Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\b1\12\f1\7a2f39b30d6780ae9f2be9a52056595e0d97c1b4531d183085 Building wheel for psutil (setup.py): started Building wheel for psutil (setup.py): finished with status 'done' Created wheel for psutil: filename=psutil-5.8.0-cp310-cp310-win_amd64.whl size=246135 sha256=834ab1fd1dd0c18e574fc0fbf07922e605169ac68be70b8a64fb90c49ad4ae9b Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\12\a3\6d\615295409067d58a62a069d30d296d61d3ac132605e3a9555c Building wheel for pygments-lexer-solidity (setup.py): started Building wheel for pygments-lexer-solidity (setup.py): finished with status 'done' Created wheel for pygments-lexer-solidity: filename=pygments_lexer_solidity-0.7.0-py3-none-any.whl size=7321 sha256=46355292f790d07d941a745cd58b64c5592e4c24357f7cc80fe200c39ab88d32 Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\36\fd\bc\6ff4fe156d46016eca64c9652a1cd7af6411070c88acbeabf5 Building wheel for varint (setup.py): started Building wheel for varint (setup.py): finished with status 'done' Created wheel for varint: filename=varint-1.0.2-py3-none-any.whl size=1979 sha256=36b744b26ba7534a494757e16ab6e171d9bb60a4fe4663557d57034f1150b678 Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\39\48\5e\33919c52a2a695a512ca394a5308dd12626a40bbcd288de814 Building wheel for websockets (setup.py): started Building wheel for websockets (setup.py): finished with status 'done' Created wheel for websockets: filename=websockets-9.1-cp310-cp310-win_amd64.whl size=91765 sha256=a00a9c801269ea2b86d72c0b0b654dc67672519721afeac8f912a157e52901c0 Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\79\f7\4e\873eca27ecd6d7230caff265283a5a5112ad4cd1d945c022dd Building wheel for wrapt (setup.py): started Building wheel for wrapt (setup.py): finished with status 'done' Created wheel for wrapt: filename=wrapt-1.12.1-cp310-cp310-win_amd64.whl size=33740 sha256=ccd729b6e3915164ac4994aef731f21cd232466b3f6c4823c9fda14b07e821c3 Stored in directory: c:\users\alaiy\appdata\local\pip\cache\wheels\8e\61\d3\d9e7053100177668fa43216a8082868c55015f8706abd974f2 Successfully built bitarray lru-dict parsimonious psutil pygments-lexer-solidity varint websockets wrapt Failed to build cytoolz Installing collected packages: toolz, eth-typing, eth-hash, cytoolz, six, pyparsing, eth-utils, varint, urllib3, toml, rlp, pyrsistent, pycryptodome, py, pluggy, parsimonious, packaging, netaddr, multidict, iniconfig, idna, hexbytes, eth-keys, colorama, charset-normalizer, certifi, base58, attrs, atomicwrites, yarl, typing-extensions, requests, python-dateutil, pytest, multiaddr, jsonschema, inflection, eth-rlp, eth-keyfile, eth-abi, chardet, bitarray, async-timeout, websockets, wcwidth, tomli, sortedcontainers, semantic-version, regex, pywin32, pytest-forked, pyjwt, pygments, protobuf, platformdirs, pathspec, mythx-models, mypy-extensions, lru-dict, ipfshttpclient, execnet, eth-account, dataclassy, click, asttokens, aiohttp, wrapt, web3, vyper, vvm, tqdm, pyyaml, pythx, python-dotenv, pytest-xdist, pygments-lexer-solidity, py-solc-x, py-solc-ast, psutil, prompt-toolkit, lazy-object-proxy, hypothesis, eth-event, eip712, black, eth-brownie Running setup.py install for cytoolz: started Running setup.py install for cytoolz: finished with status 'error' PIP STDERR ---------- WARNING: The candidate selected for download or install is a yanked version: 'protobuf' candidate (version 3.18.0 at https://files.pythonhosted.org/packages/74/4e/9f3cb458266ef5cdeaa1e72a90b9eda100e3d1803cbd7ec02f0846da83c3/protobuf-3.18.0-py2.py3-none-any.whl#sha256=615099e52e9fbc9fde00177267a94ca820ecf4e80093e390753568b7d8cb3c1a (from https://pypi.org/simple/protobuf/)) Reason for being yanked: This version claims to support Python 2 but does not ERROR: Command errored out with exit status 1: command: 'C:\Users\alaiy\.local\pipx\venvs\eth-brownie\Scripts\python.exe' -u -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\\Users\\alaiy\\AppData\\Local\\Temp\\pip-install-d1bskwa2\\cytoolz_f765f335272241adba2138f1920a35cd\\setup.py'"'"'; __file__='"'"'C:\\Users\\alaiy\\AppData\\Local\\Temp\\pip-install-d1bskwa2\\cytoolz_f765f335272241adba2138f1920a35cd\\setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d 'C:\Users\alaiy\AppData\Local\Temp\pip-wheel-pxzumeav' cwd: C:\Users\alaiy\AppData\Local\Temp\pip-install-d1bskwa2\cytoolz_f765f335272241adba2138f1920a35cd\ Complete output (70 lines): ALERT: Cython not installed. Building without Cython. running bdist_wheel running build running build_py creating build creating build\lib.win-amd64-3.10 creating build\lib.win-amd64-3.10\cytoolz copying cytoolz\compatibility.py -> build\lib.win-amd64-3.10\cytoolz copying cytoolz\utils_test.py -> build\lib.win-amd64-3.10\cytoolz 

Answer: Managed to get it working with python 3.10.1 on Win10 x64 installing cython and cytoolz first: python -m pip install --user cython python -m pip install --user cytoolz python -m pip install --user eth-brownie  https://github.com/eth-brownie/brownie/issues/1315