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Analysis of common status code to websites running on an ECS instance

Last Updated: Dec 29, 2020

Disclaimer: This article may contain information about third-party products. Such information is for reference only. Alibaba Cloud does not make any guarantee, express or implied, with respect to the performance and reliability of third-party products, as well as potential impacts of operations on the products.

Overview

This article describes the analysis of common status code errors when you run a website on an ECS instance.

Detail

The error report is complex. The following are common errors.

  • Error 403: The following describes the specific error reported in the 403 error message.
    • 403.1 the error was caused by the prohibition of execution of access. This error occurs when you attempt to execute a CGI, ISAPI, or other executable program from a directory that does not allow program execution.
    • 403.2 error is caused by Read access being banned. This error is caused because no default web page is available and directory browsing is not enabled for the directory, or the directory where the HTML page to be displayed resides is marked as "executable" or "script" permissions only.
    • The 403.3 error is caused by write access being banned. This error occurs when you try to upload a file to a directory or modify a file in a directory that does not allow write access.
    • The 403.4 error is caused by requiring SSL. You must use HTTPS in the address of the webpage you want to view.
    • The 403.5 error is caused by a Web browser that requires a 128-bit encryption algorithm. This error occurs if your browser does not support 128-bit encryption algorithm, you can connect to the Microsoft website for browser upgrade.
    • The 403.6 error was caused by the rejection of the IP address. If the server has a list of IP addresses that cannot access the site, and the IP address you are using is in the list, you will return this error message.
    • 403.7 error because customer certificate was requested. This error is returned when the browser requires that the resource to be accessed have a secure sockets layer (SSL) client certificate that the server can recognize.
    • 403.8 the error was caused by banning site access. If the server has a list of DNS names that cannot be accessed by the site, and the DNS name you use is in the list, this information will be returned. Please note the difference between 403.6 and 403.8 errors.
    • The 403.9 error is caused by too many connected users. This error will be returned when the Web server is busy and cannot process requests due to excessive traffic.
    • 403.10 errors are caused by invalid configuration. This error is returned when you attempt to execute a CGI, ISAPI, or other executable program from a directory that does not allow program execution.
    • The 403.11 error is due to a password change and does not have permission to view the page.
    • The 403.12 error is due to access denied by the mapper. The Web page to be viewed requires the use of a valid customer certificate, and when the customer certificate mapping does not have permission to access the Web site, it will return an error that the mapper denies access.
    • The 403.13 error is caused by the fact that the customer certificate used by the Web page that needs to be viewed requires the use of a valid customer certificate has been revoked or it cannot be determined whether the certificate has been revoked.
    • 403.14 error the Web server is configured to not list the contents of this directory, rejecting the directory listing.
    • 403.15 the error was caused by too many customer access licenses. This error is returned when the server exceeds its customer access license limit.
    • 403.16 the error was caused by the customer certificate not being trusted or invalid.
    • 403.17 the error is caused by the expiration of the customer's certificate or not yet effective.
  • 404 error: the 404 error is mainly reported when the page is not displayed properly or the link of the page is faulty. This indicates that the web page that the link directs to does not exist, that is, the original web page URL is invalid. When the Web server receives such a request, it returns a 404 status code, telling the browser that the requested resource does not exist. The common causes of this error include the following:
    • The website cannot be accessed through the requested port.
    • The web service extension lockdown policy blocks this request.
    • The MIME map policy blocks this request.
    • The website has been updated with a new version, but some modules use the original modules. Files called by the original modules have been deleted or their paths have been transferred.
    • The error message returned because the Accessed script or CSS file that is being traced is invalid but the call code still exists.
    • A directory is deleted directly (as a result, the "404 Not Found" error is returned when files in the directory are crawled for a period of time).
    • Original URLs are inaccessible due to changes in URL generation rules, file renaming or relocation, and a spelling error.
  • 502 error: when the test access error 502 bad gateway is reported, this is caused by an exception in the Web program configuration. We recommend that you check Web application parameters to verify whether any exceptions have been set based on Web access logs.
  • Error 503: The 503 error is an HTTP status code, which belongs to the same web page status error code as the 404 error. The former is a return state of server errors, whereas the latter is a state returned by a web program without relevant results. The 503 error may be caused by the following reasons.
    • The network administrator may close the application pool to perform maintenance.
    • The application pool queue was full when the request arrived.
    • Application pool identity is not using a predefined account: network service. If you have configured your own identity, but the configured user does not belong to the IIS_WPG Group,
    • The application pool enables CPU watch and sets the CPU usage to exceed a certain percentage to close the application pool. asp,. aspx) execution efficiency is not high, it will cause the CPU to be occupied for a long time, and eventually reach the set percentage, thus causing the application pool to be closed.
    • The value for the request queue limit of the Performance tab of the application pool is too small and defaults to 1000.
    • Delete a directory directly. (as a result, 404 Not Found is displayed when files in the directory are crawled for a period of time.)
    • Original URLs are inaccessible due to changes in URL generation rules, file renaming or relocation, and a spelling error.
    • The site is being attacked. For the latest attack type, it is actually a derivative of DDoS. This mechanism locates thousands of IP addresses, sends a request to Apache on the server at the same time, and immediately disconnects, leaving Apache in the waiting state. As a result, the Apache thread is fully filled up, causing a server crash. Therefore, in order to ensure the interests of most customers, we have set a limit of 64 PHP requests per 19seconds for each space. Common image requests and HTML requests are not included.
    • This program takes up too many PHP threads. In some programs, these threads are not properly optimized. Several PHP threads may be generated with one click, or even dozens of threads. In this way, 64 PHP threads can be filled during this period with a few clicks. Therefore, 503 error occurred. It is recommended to optimize the program and minimize statements such as require (request).

Scope

  • Elastic Compute Service