How to Fix 407 Proxy Authentication Required Error

By ErrorFix · Updated October 26, 2026 · 6 min read

What 407 Proxy Authentication Required means

HTTP status 407 is the proxy version of the familiar 401 login error. When you browse through a proxy — common on school, office, and corporate networks, and with commercial proxy services — your request goes to the proxy first, and the proxy forwards it to the website. A 407 means the proxy stopped your request at its own door and asked for authentication: it will not forward anything until you prove you are allowed to use it.

This is different from a problem with the website itself. The site may be perfectly healthy; your request simply never reached it. That is why retrying the page, clearing the site cookies, or switching browsers often does nothing: the block is happening one hop earlier, at the proxy, and only valid proxy credentials or a corrected proxy setting will clear it.

Proxies ask for authentication for a good reason. They control who can use the network, filter traffic, log access, and enforce company or school policies. On a home connection with no proxy configured, a sudden 407 usually means something changed your settings — a VPN app, a browser extension, or leftover settings from a previous network — and removing that stray configuration is the fix. On a managed network, the fix is almost always the right username and password, entered once, cleanly.

Common causes

• Missing or wrong proxy credentials: no username and password were supplied, or the ones saved are outdated after a password change.
• Wrong proxy address or port: settings point at a different proxy than the one your credentials belong to, so the login is always rejected.
• Browser overriding system proxy settings: a manual configuration or a proxy extension routes traffic through a proxy you no longer have access to.
• Locked or expired proxy account: repeated failed logins, an expired password, or a deactivated account stops authentication from succeeding.
• Authentication method mismatch: the proxy expects one login method, such as NTLM or Kerberos, while the client is configured to send another.

How to fix the 407 Proxy Authentication Required error — step by step

Start with the visitor steps (1–5). If you run the proxy, step 6 is where most persistent 407s get fixed.

1. Sign in again with the correct proxy credentials. When the browser prompts for proxy credentials, enter the username and password exactly as your network admin or proxy provider gave them, watching for caps lock, trailing spaces, and autofill that may have inserted an old password. If the prompt keeps reappearing, cancel it and sign in once more rather than hammering the retry button, since repeated failed logins can lock the account. If you never received credentials, ask your admin or provider for them: a 407 cannot be fixed without a valid login for that proxy.
2. Check your system proxy settings. Open your system proxy settings: on Windows, go to Settings, then Network and internet, then Proxy, and check whether Use a proxy server is on and whether the address and port match the ones your network requires. On macOS, open System Settings, then Network, select your connection, click Details, then Proxies, and confirm the web proxy entries. A single wrong digit in the address or port sends your traffic to the wrong proxy, which answers with a 407 because your credentials do not belong to it.
3. Make sure your browser uses the system proxy. Open your browser settings and confirm it is set to use the system proxy rather than a manual or extension-managed configuration that overrides it. In Chrome, go to Settings, then System, and open your computer proxy settings; in Firefox, go to Settings, then General, then Network Settings, and choose Use system proxy settings unless your network gave you a specific manual setup. Disable VPN or proxy browser extensions one at a time and retry, since an extension can silently route traffic through a proxy you no longer have access to.
4. Clear stale proxy credentials and cached auth data. If you recently changed your network password, your browser or operating system may still be sending the old one. On Windows, open Credential Manager, then Windows Credentials, and remove any saved proxy credentials so the next prompt asks you fresh. Clear the browser cache and cookies for the affected site, close the browser completely, and reopen it so no stale session survives. On a work device, also sign out and back in to your network account, since a changed domain password invalidates saved proxy logins until you refresh them.
5. Test without the proxy to isolate the problem. Temporarily turn the proxy off in your system settings and try loading a normal website. If pages load fine without the proxy, the proxy itself is the problem: its credentials, its allowlist, or its service. If pages still fail, the problem is your connection or DNS, not the proxy, and you should troubleshoot those instead. Remember to turn the proxy back on before you finish if your school, office, or provider requires it, since some networks block direct internet access entirely.
6. Network admin: check the proxy account and authentication method. If you run the proxy, check that the user account is active, not locked, and assigned to a group allowed through the proxy, and confirm the password has not expired under your rotation policy. Check that the proxy authentication method matches what clients send: a proxy expecting NTLM or Kerberos will reject basic-auth credentials, and a proxy expecting basic auth will reject a client configured for integrated Windows authentication. Review the proxy logs for the failing requests to see whether they carry no credentials, expired credentials, or credentials for the wrong realm.

Did this fix it? Quick checklist

• The proxy login prompt accepts your credentials and pages load
• Your system proxy address and port match what your network requires
• It works with extensions disabled and after saved credentials are cleared
• Network admins: affected accounts are active, unlocked, and in the allowed group

If the error only appears on one browser, check that browser for its own manual proxy configuration or a proxy extension — switching it to the system proxy usually clears it. On the admin side, if 407s spiked right after a password rotation or a proxy change, check the authentication method and the account lockout policy first, since those two changes cause most sudden waves of false 407s.