How to fix 407 proxy authentication error

Quick checks that solve most cases

• Confirm proxy login: Re-enter the correct username and password. Watch for typos and case sensitivity.
• Verify server and port: Make sure the proxy host and port match what your provider or IT gave you.
• Check your plan or access: Ensure your proxy subscription is active, your IP is allowlisted, and you have not hit a connection limit.
• Match the auth method: Some proxies need Basic, NTLM, Kerberos, or Negotiate. Use a client that supports it.
• Try a different proxy endpoint: If your provider offers multiple regions or gateways, switch and test.

Sign in where the network requires it

• Connect VPN first: Many corporate proxies work only on VPN. Connect, then retry.
• SSO or captive portal: Open a browser and visit any site to trigger sign-in. Complete SSO/MFA if prompted.
• Fix time sync: Kerberos and SSO can fail if your device clock is off. Sync your system time.
• SSL inspection certificate: If your company inspects HTTPS, install the corporate root certificate as IT directs.

Test quickly with curl

• Basic test: curl -x http://user:pass@host:port https://example.com -I
• If it works with curl, your network and credentials are fine. The issue is likely in your app’s proxy settings.
• If it fails, recheck credentials, host, port, and auth scheme.

Fix 407 proxy authentication error in browsers and OS

Windows and macOS system settings

• Open system proxy settings: On Windows, search “Proxy settings.” On macOS, System Settings > Network > Proxies.
• Disable stale entries: Turn off old manual proxies or old PAC files you no longer use.
• Add correct proxy: Enter host, port, and credentials if required.
• Bypass local addresses: Enable “Bypass proxy for local addresses” or add domains to the bypass list.
• Clear stored credentials: On Windows, use Credential Manager; on macOS, use Keychain Access. Remove old proxy logins and sign in fresh.

Chrome, Edge, and Firefox

• Use system proxy: Most setups rely on system settings. Restart the browser after changes.
• Clear cache and cookies: Remove cached 407 loops, then retry.
• Disable extensions: A VPN, ad blocker, or security add-on may force a bad proxy. Test in Incognito/Private mode.
• Check PAC/WPAD: If your company uses a PAC file or auto-detect, make sure the PAC URL is reachable and correct.

Fix it in popular tools

Environment variables (Windows, macOS, Linux)

• Set both uppercase and lowercase: HTTP_PROXY/HTTPS_PROXY and http_proxy/https_proxy.
• Example: export HTTPS_PROXY=”http://user:pass@host:port”
• Bypass domains: Set NO_PROXY (or no_proxy), for example: NO_PROXY=”localhost,127.0.0.1,.company.com”

Git

• Set proxy: git config –global http.proxy http://user:pass@host:port
• Unset if not needed: git config –global –unset http.proxy
• For HTTPS: git config –global https.proxy http://user:pass@host:port

npm and Node tools

• Set proxy: npm config set proxy http://user:pass@host:port
• Set HTTPS proxy: npm config set https-proxy http://user:pass@host:port
• Unset: npm config delete proxy; npm config delete https-proxy

pip and Python CLIs

• Use environment variables as above, or create pip.ini/pip.conf with the proxy URL.
• Test: pip install requests — then confirm it works behind the proxy.

Fix it in code

Node.js (Axios)

• Axios proxy option: axios.get(url, { proxy: { host: ‘host’, port: 8080, auth: { username: ‘user’, password: ‘pass’ } } })
• For HTTPS over HTTP proxy, use an agent (for example, https-proxy-agent) and set httpAgent/httpsAgent.
• If the library does not handle auth, add the Proxy-Authorization header with a valid token or Basic base64.

Python (requests)

• Proxies dict: requests.get(url, proxies={‘http’: ‘http://user:pass@host:port’, ‘https’: ‘http://user:pass@host:port’})
• NTLM/Kerberos: Use requests-ntlm or requests-kerberos if your proxy requires it.

Java

• System properties: -Dhttp.proxyHost=host -Dhttp.proxyPort=port (and https.*)
• Authentication: Provide a java.net.Authenticator that returns your proxy username and password.
• OkHttp: client.proxy(new Proxy(…)).proxyAuthenticator((route, response) -> …)

When the proxy is the problem

• Account or credits expired: Renew or top up.
• IP not allowlisted: Ask the provider or IT to add your public IP.
• Too many connections: Reduce concurrency or buy more capacity.
• Region or geo blocked: Switch to a different proxy location.
• Auth scheme mismatch: Your client only sends Basic, but the proxy expects NTLM/Kerberos, or vice versa.
• TLS interception issues: Install the proxy’s root certificate or disable inspection for your target (IT action).

(Source: https://www.inc.com/tony-manganiello/your-employees-are-already-using-ai-tools-whether-you-know-it-or-not/91380123)

For more news: Click Here

FAQ