The Avi Load Balancer responds with various error codes when an HTTP or HTTPS communication fails. This section describes some common HTTP error codes returned from the server.

The Avi Load Balancer responds with the following HTTP error codes:

  • 4xx error codes: If there are errors in client requests, the Avi Load Balancer responds with 4xx.

  • 5xx error codes: If a failure occurs in load balancing or there is an error communicating with the server.

  • 500 error code: If there are internal errors on the Avi Load Balancer, for example, memory allocation failure or DataScript exception.

Error Codes Details

Error Codes

Error

Description

400

Bad Requests

This status code indicates that the Avi Load Balancer encountered an error while parsing the request line.

Example:

  • Invalid request line, header line.

  • Invalid Host or HTTP Version.

  • Failure to parse URI.

401

Request Unauthorized

This error status response code indicates ldap authentication failure.

Example:

  • One or more LDAP headers missing.

  • Missing credentials.

  • Login failed.

403

Request Forbidden

This error status response code indicates that the Avi Load Balancer has received and recognized the request but denied to proxy it. This error can occur when the user requesting a particular resource does not have the necessary permissions.

Example:

  • This is the WAF's default error code, when running in enforcement mode.

405

Method not allowed

This occurs when the requested GET method is not valid for accessing a particular resource or applicaiton.

Example:

  • RUM allows only GET/POST Methods RUM args from the client could not be processed.

408

Request timeout

The Avi Load Balancer will terminate the unused connection due to request timed out while it waits for request headers or body from the client.

413

Payload too large

This status code indicates that the request payload size is too large. Following are the steps for troubleshooting 414 issue:

  • Check application profile's DOS settings for client Post request body size.

  • WAF could also return this error code when running in enforcement mode. Check upload limits in the WAF Profile.

414

URI too long

This status code indicates that the URI requested by the client is longer than the virtual service is configured to allow. For troubleshooting, check client request Size under application profile's DOS settings.

416

Range Not Satisfiable

This response code indicates that the virtual service cannot serve the requested ranges. This might be invalid value for range header.

429

Too Many Requests

This error code indicates that user has sent too many requests in a given duration. Check DOS Settings in applicaiton profile and rate limit settings of the HTTP policy.

470

Close connections

This status code indicates that the Avi Load Balancer closed the connection due to the following reasons:

  • HTTP Network or Security Policy action set to Close Connection.

  • Data Script execute avi.http.close_conn().

  • Pool fail action set to Close Connection.

471

Request header too large

This status indicates that one of the http request headers is too large to process. Check client header size under DOS settings of the application profile.

472

Client certificate verification failed

This status indicates that the Avi Load Balancer failed to verify SSL certificate of the client.

473

Client failed to send certificate

This status indicates that the Avi Load Balancer closed the connection because it required client to present a certificate, but client failed to send a certificate to verify. To troubleshoot, check client SSL certificate validation section under Application Profile Security setting and client's SSL certificate configuration under application profile's security setting.

474

HTTP request to HTTPs port

This status indicates that the client sent a HTTP request in plain text to HTTPs service port configured for virtual service.

475

Client closed connection while server is processing the request

This status indicates that the client closed the connection while the Avi Load Balancer was proxying it to the server.

500

Internal server error

Internal errors such as memory allocation failures, or unexpected inconsistent configuration in the request.

502

Bad Gateway

This happens when there are errors proxying the request to the server such as server certificate verification failure or server abruptly closes the connection. For example:

  • Failed to verify the upstream server's Certificate.

  • SSL Pool's common name check failed.

503

Service unavailable

Connection to upstream server failed due to the following reasons:

  • Upstream selected server was down.

  • Pool's max concurrent connections per server was reached.

504

Gateway timeout

This response code indicates connection timeout for one of the below reasons:

  • Timeout while reading or writing body from or to server.

  • Timeout while writing body to the client.