ERR_PROXY_CONNECTION_FAILED: What It Means and How to Fix It

Full Diagnostic Checklist

Go through the items in order and stop at the first one that fixes the problem.

1. Is the proxy actually configured?

In Chrome, open Settings → System → "Open your computer's proxy settings" (in Edge: Settings → System and performance). This opens the Windows settings: Settings → Network & internet → Proxy (on macOS: System Settings → Network → your connection → Details → Proxies). If "Use a proxy server" is off but the error persists, check "Use setup script" and "Automatically detect settings", proxy extensions (chrome://extensions) and policies (chrome://policy). If the toggle is on, continue.

• Sources:
• Chromium docs: Proxy support in Chrome (net/docs/proxy.md)
• Microsoft Support: Use a proxy server in Windows

2. Incorrect host or port

The most common mistakes are a typo in the server address, an extra digit in the port, or swapped host and port values. Check both fields separately. If you have access to the proxy management console, in the "My assets" section (where the console stores everything you have purchased), copy HOST, PORT, USERNAME, and PASSWORD instead of entering them manually. For more details about address, port, and authentication method, see the proxy address and port guide.

• proxy address and port guide

3. Wrong protocol: HTTP or SOCKS5

Proxy servers operate on two main protocols: HTTP and SOCKS5. If the settings specify one protocol but the proxy runs on another, the connection will be rejected. Each IP in "My assets" uses a single protocol: it is selected at purchase, and there is no protocol switch there. Chrome and Edge do not support SOCKS5 with a username and password, so for the browser use an HTTP asset (port 2222 on Proxy302); keep authenticated SOCKS5 for tools that support it, such as curl with socks5h://.

• Sources:
• Chromium docs: Proxy support in Chrome (net/docs/proxy.md)
• Proxy302 product facts and price list

4. Firewall or antivirus

Protection software may block outgoing connections on non-standard ports. Check the firewall and antivirus logs and add an exception for the browser and the proxy port; you do not need to turn protection off entirely. Some antivirus programs also intercept TLS traffic, and even if a connection to the proxy is established, certificate verification may interrupt it at the intermediate node.

5. Credentials

Wrong credentials usually do not cause this error: the browser shows a sign-in prompt, a 407 error or ERR_TUNNEL_CONNECTION_FAILED instead, and some servers simply close the connection. So check the username and password, but first make sure the host and port are reachable (items 1–4), and check them again if a different error appears after you fix those items. Copy the username and password in full, including special characters that are easy to miss when typing by hand. For the 407 error, see the proxy authentication guide.

• proxy authentication guide

• Sources:
• Chromium source: net error list (net_error_list.h)

6. IP whitelist

Some services restrict proxy access only to pre-registered IP addresses. If you are connecting from an address not on the whitelist, the request is rejected at the entry point. Check in the console whether IP whitelisting is on, and add the public IP of your current network to it. This causes ERR_PROXY_CONNECTION_FAILED only when the proxy drops the TCP connection outright; if the connection opens and access is then refused, the browser shows a credentials prompt or ERR_TUNNEL_CONNECTION_FAILED instead.

• Sources:
• Chromium source: net error list (net_error_list.h)

7. Expired term or exhausted limit

Rented proxies expire; after the end date the old credentials stop working. On pay-per-GB plans the purchased traffic can run out. Check in My assets whether the plan is still active and how much traffic is left. As with the previous item, this causes ERR_PROXY_CONNECTION_FAILED only when the proxy drops the TCP connection outright.

• Sources:
• Chromium source: net error list (net_error_list.h)

8. DNS problems

If the proxy is identified by domain name rather than IP, the error may arise from incorrect DNS operation on your device or on the provider's side. Try manually specifying public DNS servers (for example, 1.1.1.1 or 8.8.8.8), clear the DNS cache, and retry the connection.

9. System and browser proxy settings

Chrome and Edge have no proxy settings of their own: they use the system settings unless a proxy is set by an extension, a policy or the --proxy-server flag. Firefox has its own settings. If you use third-party applications, check whether they redirect traffic through their own proxy client, which intercepts the connection before the browser does.

• Sources:
• Chromium docs: Proxy support in Chrome (net/docs/proxy.md)

Checking the proxy via curl

To rule out the browser, run the request from a terminal. The curl command sends a request through the specified proxy and shows what response the server returned.

Checking the proxy via curl: example

# HTTP proxy
curl -x http://LOGIN:PASSWORD@HOST:PORT https://ipinfo.io/json

# SOCKS5 (DNS is also resolved through the proxy)
curl -x socks5h://LOGIN:PASSWORD@HOST:PORT https://ipinfo.io/json

Example only: replace the placeholder values with your own.

Checking the proxy via curl, continued

If the proxy is working — the response will be JSON with the exit IP address, country, and provider. If a timeout error appears instead of a response — check the host, port, and network availability. If it returns 407 or "User was rejected" — incorrect credentials. More details about checking the address and exit IP location are described in the proxy checking guide.

• proxy checking guide

Is the problem with the proxy or the website itself?

A simple test tells you which it is: turn the proxy off and open the same site. If the website loads without the proxy, the problem is with the proxy settings or its operation. If the website does not open directly either, the problem is on the site's side or with your internet provider.

One more clue: does the ERR_PROXY_CONNECTION_FAILED error appear on all websites or only on one? If on all, first check the availability of the proxy itself via curl. If the error appears on only one site, check for a PAC script or an extension that sends that site through a different proxy.

When choosing a proxy for work tasks, match the protocol and plan to your task: rotating residential proxies suit regional testing, a static ISP proxy suits work from one fixed address. A more detailed comparison of formats is available on the proxy options page.

The gateway for Proxy302 rotating residential proxies is proxy.proxy302.com: port 2222 for HTTP and 3333 for SOCKS5.

• proxy options page

Why does the proxy work in one browser but give an error in another?

Chrome and Edge use the system proxy settings unless an extension, a policy or the --proxy-server flag sets another proxy; Firefox has its own settings. Check the browser where the error occurs: a different address or port may be set there, or an extension may be sending traffic to another proxy.

What to do if curl shows the proxy is working but the browser still gives an error?

If curl returns a correct response with the exit IP, but Chrome or Edge show ERR_PROXY_CONNECTION_FAILED, the problem is in the browser. Clear cache and cookies, disable extensions that may change network settings, and check chrome://policy and the browser's launch flags for a proxy set there. If your proxy is SOCKS5 with a username and password, the browser cannot use it: switch to an HTTP asset.

The error appears only on one website. Is this a proxy problem?

Not necessarily. Open the site without the proxy: if it opens, check the proxy address and port again; if it does not, the problem is on the site's side or with your internet provider.

How to understand that the proxy is actually working and not just "silent"?

Check via curl with a request to ipinfo.io: the response will explicitly show the exit IP address, country, and provider. If a timeout, connection error, or rejection appears instead of a response — the proxy is not accepting requests. If the response arrives but the IP does not match the expected one — check the settings to see if another proxy is connected higher up in the chain.

How to do it with Proxy302

Rotating residential proxies fit this task: you choose the exit country (195+ countries and regions, with state and city on lines that support it) and pay per GB, so you pay only for the traffic you use. The rotating residential page has the setup. The table below is an example only: our latest hourly check of ChatGPT through exits in 7 countries.

• rotating residential page

Measured exits: ChatGPT from 7 countries

Hourly check of the Proxy302 probe, 23 October 2026, 15:47 UTC: one request to ChatGPT per country through a dynamic residential exit, using the public Proxy302 entry. Only the first three octets of an IP are public. One sample per country, not an average; later checks will differ.

• Sources:
• Proxy302 hourly connectivity check

How to do it with Proxy302: steps

1. Step 1

   Open the rotating residential page, choose the line, and keep Protocol on HTTP or choose SOCKS5, then click Review cost and generate.

2. Step 2

   Open My assets (the console page that holds everything you bought) and copy HOST, PORT, USERNAME and PASSWORD. The Connect page shows a ready example with your own endpoint.

3. Step 3

   Enter the details in the browser or tool you are setting up.

4. Step 4

   Confirm the exit with https://ipinfo.io/json through the proxy.

5. Step 5

   From mainland China, start the helper tool from the Connect page first and keep it open while you use the proxy.

   • Helper tool guide

Prices and limits

The Budget line costs US$1.50 per GB, US$1.35 per GB in a 100 GB package and US$1.20 per GB at 300 GB. There is no free trial, and the smallest purchase is 1 GB.

• Sources:
• Proxy302 product facts and price list

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