This guide explains the most common proxy server HTTP CONNECT response status codes, what each means, and how to fix them. From successful connections and authentication issues to traffic limitations, each error is explained with possible causes and actionable resolutions that can help you maintain seamless proxy server operations.

Whether it’s because of a blocked port or because you’ve exceeded your plan limits, this guide will get you over the hump with quick identification of any problem at hand and an easy fix. The examples and recommendations are based on real proxy management practices, including those used by DataImpulse customers.

DataImpulse is a provider of high-grade residential, datacenter, and mobile proxy solutions across 195 countries. Proxies are ethically sourced and traffic doesn’t expire. No subscription is required. 

Proxy Server HTTP CONNECT Response Status Codes

200 OK

Description: The request has succeeded, and the proxy server has successfully established a connection to the remote server.

When Returned: This status code is returned when the proxy server processes a valid CONNECT request without any issues, allowing the client to communicate with the target server through the established tunnel.

400 Bad Request

Description: The proxy server could not understand the request due to invalid syntax.

Possible Causes:

• Malformed CONNECT request.
• Missing or incorrect headers.
• Syntax errors in the request line.

Resolution:

• Ensure that the CONNECT request is correctly formatted according to the HTTP specification.
• Verify all required headers and parameters are included and correctly structured.

403 PORT_BLOCKED

Description: The connection attempt is made to a blocked port.

Possible Causes:

• The destination port is restricted by the service’s security policies.
• Attempting to access ports that are known for malicious activities.

Resolution:

• Use an allowed port for the connection.
• Consult the documentation or customer support for a list of permitted ports.

403 SITE_PERMANENTLY_BLOCKED

Description: Access to the specified site has been permanently blocked by the proxy server.

Possible Causes:

• The site is blacklisted due to security concerns or policy restrictions.
• The site may host malicious content or violate usage policies.

Resolution:

• Avoid accessing the blocked site.
• If access is required, contact the customer support to discuss the possibility of unblocking.

403 HOST_BLOCKED

Description: The access to the specified site has been blocked by user in the current plan settings.

Possible Causes:

• User-level settings or preferences have been configured to block the site.

Resolution:

• Review and adjust personal blocking settings or preferences.

407 Proxy Authentication Required

407 NO_USER

Description: The user’s plan doesn’t exist.

Possible Causes:

• Incorrect proxy plan credentials is provided during authentication.
• The user account has been deleted or is not registered.

Resolution:

• Verify and correct username and password in your authentication credentials.
• Register a new account if necessary or contact customer support for assistance.

407 TRAFFIC_EXHAUSTED

Description: The traffic limit of the plan is exceeded.

Possible Causes:

• Data transfer limits have been reached.

Resolution:

• Add traffic to an existing plan.
• Create a new plan.

407 THREADS_EXHAUSTED

Description: The threads limit of the plan is exceeded.

Possible Causes:

• Exceeding the maximum number of concurrent connections allowed by your plan.

Resolution:

• Close unnecessary connections or applications.
• Consult customer support to add more concurrent threads.

407 PORT_NOT_ALLOWED

Description: The sticky sessions port used is not allowed by current plan settings.

Possible Causes:

• Attempting to use a port that is not included in your plan.
• Misconfigured port settings in your application.

Resolution:

• Use a port that is permitted under your current plan.
• Adjust your application settings to comply with allowed ports.

407 USER_BLOCKED

Description: The user’s current plan has been blocked.

Possible Causes:

• Violation of terms of service or acceptable use policies.
• Suspicious or fraudulent activities detected on the account.

Resolution:

• Contact customer support to inquire about the block and request reinstatement.
• Review and adhere to the service’s terms and policies to prevent future issues.

500 Internal Server Error

Description: The proxy server encountered an unexpected condition that prevented it from fulfilling the request.

Possible Causes:

• Server-side errors or misconfigurations.
• Temporary issues with the proxy server’s infrastructure.

Resolution:

• Retry the request after a short period.
• If the problem persists, contact the customer support team for assistance.

502 NO_HOST_CONNECTION

Description: There is no connection to the host specified in the CONNECT request.

Possible Causes:

• Network connectivity issues between the proxy and the target host.
• The destination server is offline or unreachable.

Resolution:

• Retry the request after a short period.
• Verify that the target server is operational and accessible.

503 NO_RAY

Description: There are no proxies available based on the targeting parameters specified in the request.

Possible Causes:

• All proxies matching the requested criteria are currently in use.
• The targeting parameters are too restrictive, limiting the pool of available proxies.

Resolution:

• Modify the targeting parameters to be less restrictive.
• Try the request again later when resources may have freed up.
• Contact support to discuss options for additional resources.

Conclusion

Proxy status error codes can seem like a frustrating roadblock to accessing your target data, but with the right knowledge, most of these issues are easy to troubleshoot. By understanding the meaning behind each error and following the recommended steps for resolution, you can quickly overcome these challenges and maintain smooth, uninterrupted access to your proxy services. With this guide in hand, you’ll be well-equipped to handle common proxy errors and get back to achieving your goals efficiently.

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