Hey there, let's get this pip installation issue sorted out! That 403 Forbidden error means your pip request is getting blocked by a proxy server—either the system proxy you're using doesn't have permission to access PyPI, or pip is picking up a proxy setting that's not working correctly.

Here are some straightforward fixes you can try, in order of simplicity:

1. Install Without Proxy (Quick Test) #

First, try telling pip to skip using any proxy entirely with this command:

pip install selenium --no-proxy

This is the fastest way to confirm if the proxy is the root cause.

2. Clear System Proxy Environment Variables #

Sometimes your Windows system has proxy variables set that pip automatically uses. Let's check and clear them temporarily:

• Open your command prompt and run these to see if proxies are configured:

  echo %HTTP_PROXY%
  echo %HTTPS_PROXY%
  

• If you see proxy URLs returned, clear them with:

  set HTTP_PROXY=
  set HTTPS_PROXY=
  

• Now try installing selenium again with the original command:

  pip install selenium
  

3. Use a Domestic PyPI Mirror (Most Reliable for China Users) #

If the issue is accessing the official PyPI server, switching to a domestic mirror will bypass the proxy problem entirely:

• Temporary use (run this directly):

  pip install selenium -i https://pypi.tuna.tsinghua.edu.cn/simple
  

• To set it permanently (so you don't need to add the -i flag every time):
  1. Go to your user folder (e.g., C:\Users\YourUsername)
  2. Create a folder named pip
  3. Inside that folder, create a file named pip.ini with this content:

     [global]
     index-url = https://pypi.tuna.tsinghua.edu.cn/simple
     

  4. Save the file, and future pip installs will use this mirror by default.

4. Configure Correct Proxy Settings (If You Need Proxy Access) #

If you must use a proxy to access the internet, make sure you have the right credentials and settings:
Run this command, replacing the placeholders with your actual proxy details:

pip install selenium --proxy=http://your-username:your-password@proxy-address:proxy-port

Your Original Error Details #

For reference, here's the error you encountered:

(base) C:\>pip install selenium
Collecting selenium
Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 403 Forbidden'))': /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl
Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 403 Forbidden'))': /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl
Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 403 Forbidden'))': /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl
Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 403 Forbidden'))': /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl
Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 403 Forbidden'))': /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl
Could not install packages due to an EnvironmentError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Max retries exceeded with url: /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl (Caused by ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 403 Forbidden')))

内容的提问来源于stack exchange，提问作者Monkeydave