What this error means

How to fix HTTP 407 proxy authentication required error

• Confirm your proxy credentials. Make sure your username, password, and domain (if used) are correct. Try DOMAINusername if you are on Windows with NTLM or Kerberos.
• Set the proxy in your system settings and in the app. Some apps do not read system settings, so add both.
• Clear saved bad credentials. Old passwords in the browser, Keychain, or Credential Manager can cause instant 407.
• Use no_proxy to bypass local and intranet hosts. Add localhost, 127.0.0.1, and your company domains.
• Test with curl -v to see the Proxy-Authenticate header and confirm the right auth method.
• If your company inspects TLS, install the corporate root certificate so HTTPS works through the proxy.
• If nothing changes, contact IT with the exact time, URL, app, and your curl -v output.

Step-by-step fixes by environment

Browser (Chrome, Edge, Firefox)

• Sign in when prompted. Use DOMAINusername if needed.
• Windows: Open Internet Options > Connections > LAN settings. Set “Use a proxy server” or “Use automatic configuration script” if your company uses a PAC file.
• macOS: System Settings > Network > Your network > Details > Proxies. Set HTTP/HTTPS proxy or Auto Proxy (PAC).
• Clear stored creds: remove proxy entries from Password Manager (Chrome), Keychain (macOS), or Credential Manager (Windows).
• Disable extensions that intercept traffic (VPN, ad-block) and test again.
• For captive portals (hotel, airport), visit http://neverssl.com to trigger the login page.

Windows

• System proxy: Settings > Network & Internet > Proxy. Set Manual proxy or Use setup script.
• WinHTTP sync: In an elevated Command Prompt: netsh winhttp import proxy source=ie
• Show or reset WinHTTP proxy: netsh winhttp show proxy netsh winhttp reset proxy
• Credential Manager: Control Panel > Credential Manager > Windows Credentials. Remove proxy entries, then retry sign-in.

macOS

• Set proxy in System Settings as above. If a PAC URL is given by IT, use it.
• Keychain Access: search for “proxy” and remove old passwords if login fails.
• If your company uses TLS inspection, install the company root CA into System and Login keychains, mark as “Always Trust.”

Linux and the command line

• Set environment variables (replace values): export http_proxy=”http://USER:PASS@proxy.example.com:8080″ export https_proxy=”http://USER:PASS@proxy.example.com:8080″ export no_proxy=”localhost,127.0.0.1,.corp.local”
• Many tools also read uppercase: export HTTP_PROXY=”$http_proxy” export HTTPS_PROXY=”$https_proxy” export NO_PROXY=”$no_proxy”
• Test with: curl -v -U USER:PASS -x http://proxy.example.com:8080 https://example.com

Developer tools and package managers

• Git: git config –global http.proxy http://USER:PASS@proxy.example.com:8080 git config –global https.proxy http://USER:PASS@proxy.example.com:8080 If TLS inspection is used: git config –global http.sslCAInfo /path/to/corporate-ca.pem
• npm and Node.js: npm config set proxy http://USER:PASS@proxy.example.com:8080 npm config set https-proxy http://USER:PASS@proxy.example.com:8080 Use your corporate CA instead of turning off SSL. If needed: export NODE_EXTRA_CA_CERTS=/path/to/corporate-ca.pem
• pip: pip install –proxy http://USER:PASS@proxy.example.com:8080 package
• Maven (settings.xml): corptruehttpproxy.example.com8080USERPASSlocalhost|127.0.0.1|*.corp.local
• Gradle (gradle.properties): systemProp.http.proxyHost=proxy.example.com systemProp.http.proxyPort=8080 systemProp.http.proxyUser=USER systemProp.http.proxyPassword=PASS systemProp.http.nonProxyHosts=localhost|127.0.0.1|*.corp.local
• Docker: Create or edit /etc/systemd/system/docker.service.d/proxy.conf: [Service] Environment=”HTTP_PROXY=http://USER:PASS@proxy.example.com:8080″ Environment=”HTTPS_PROXY=http://USER:PASS@proxy.example.com:8080″ Environment=”NO_PROXY=localhost,127.0.0.1,.corp.local” Then run: systemctl daemon-reload && systemctl restart docker

Common causes and how to spot them

• Wrong or expired password: You may need to update your password in all places that store it.
• Wrong auth method: Proxy may require NTLM or Kerberos. The curl -v output shows Proxy-Authenticate: NTLM, Negotiate, or Basic.
• Not using domain: Try DOMAINusername or user@domain.
• Missing PAC or wrong proxy: If your company uses a PAC URL, set it. Wrong host or port always fails with 407.
• No HTTPS trust: If the proxy breaks and re-signs TLS, install the corporate root CA and point tools to it.
• Bypass not set: Add intranet sites to no_proxy or NonProxyHosts to avoid the proxy where it is not needed.
• VPN or Wi-Fi portal: Connect to VPN or complete the captive portal login first.

Prevent it from coming back

• Use system proxy settings and a PAC script so apps stay consistent.
• Store credentials in the OS manager, not in many tools scattered across your machine.
• Keep no_proxy updated for local and internal services.
• Install and maintain the corporate root CA on all devices you use.
• Keep your device time in sync for Kerberos and SSO.

When to escalate to IT

• Time of failure, your IP or device name, and the URL you tried.
• The app and version (browser, git, npm, etc.).
• curl -v output showing the 407 and Proxy-Authenticate header.
• Whether you are on VPN, Wi-Fi, or wired.

(Source: https://www.forbes.com/sites/michelletravis/2026/08/11/ai-hiring-tools-dont-just-learn-bias-ai-forms-new-biases-of-its-own)

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