Fix Proxy Authentication Failed Errors

Proxy authentication fails when the gateway cannot accept the connection credentials or the subscription cannot currently be used.

Quick answer: copy a fresh proxy line from the dashboard, test it with cURL, then check subscription activity, remaining bandwidth, password, username format, and protocol/port. Most authentication failures come from stale copied values or an inactive subscription.

Common causes

Cause	What to check
Stale password	Copy the current password from the dashboard or reset it.
Expired subscription	Confirm the subscription is active and the renewal date is in the future.
Exhausted usage	For rotating products, confirm remaining bandwidth is greater than zero.
Malformed username	Copy the generated username instead of editing suffixes manually.
Wrong protocol or port	Match HTTP or SOCKS5 with the port shown in the dashboard.
Wrong proxy format	Use the format your app expects.
IP authentication mismatch	Confirm the connecting source IP is trusted.

Step 1: Test a fresh line

Copy a current proxy string from Thunderproxy and test it with cURL:

curl --proxy "http://username:password@host:port" "https://api.ipify.org?format=json"
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If cURL works, Thunderproxy accepted the credentials. The issue is likely in your app's format, import settings, or protocol selection.

If cURL fails, continue through the checks below.

Step 2: Check subscription activity

Open the subscription in the dashboard and confirm it is active.

For automation, the Account API can return subscription status:

GET https://api.thunderproxy.com/v1/api/account?apiKey={apiKey}&activeOnly=true
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For rotating products, also check dataLeft. If usage reaches zero, the subscription may stop authenticating even when the copied username and password are correct.

Step 3: Copy the password again

If you reset a proxy password, old exported lists and saved app settings will keep using the old password.

After a password reset:

1. Copy a new proxy string from the dashboard.
2. Update every app, worker, profile, or imported list that used the old password.
3. Test one line before restarting large jobs.

Step 4: Check username format

Rotating usernames encode routing settings:

base-res-US-sid-12345678
base-dc-DE
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Do not remove required fragments or add your own suffixes. Choose settings in the dashboard, then copy the generated username.

Static ISP usernames use a fixed row suffix:

base-stc-isp-sid-0
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Do not add rotating residential or datacenter suffixes to Static ISP usernames.

Step 5: Check protocol and port

If the dashboard shows HTTP and SOCKS5, each protocol can use a different port. A valid username and password can still fail if the client uses the wrong protocol for the port.

Match all three:

• Protocol selected in your app.
• Port copied from Thunderproxy.
• Proxy URL or field format used by your app.

Step 6: Check IP authentication

For IP authentication, the gateway checks your source IP instead of username and password.

If IP authentication fails:

• Confirm the request comes from the same source IP saved in the dashboard.
• Update trusted IPs after network, VPN, cloud server, or ISP changes.
• Test user:pass authentication separately if available.

Next steps

• Test a proxy with cURL.
• Choose the right proxy format.
• Understand activity and renewals.
• Troubleshoot exported proxy lists.