HTTP Error 301 - Moved permanently

Introduction

Your Web server thinks that your URL has been permanently redirected to another URL. The client system is expected to immediately retry the alternate URL.

301 errors in the HTTP cycle

Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server:

  • Obtain an IP address from the IP name of the site (the site URL without the leading 'http://'). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).
  • Open an IP socket connection to that IP address.
  • Write an HTTP data stream through that socket.
  • Receive an HTTP data stream back from the Web server in response. This data stream contains status codes whose values are determined by the HTTP protocol. Parse this data stream for status codes and other useful information.

This error occurs in the final step above when the client receives an HTTP status code that it recognises as '301'.

Fixing 301 errors - general

The 301 response from the Web server should always include an alternative URL to which redirection should occur. If it does, a Web browser will immediately retry the alternative URL. So you never actually see a 301 error in a Web browser, unless perhaps you have a corrupt redirection chain e.g. URL A redirects to URL B which in turn redirects back to URL A. If your client is not a Web browser, it should behave in the same way as a Web browser i.e. immediately retry the alternative URL.

If the Web server does not return an alternative URL with the 301 response, then either the Web server sofware itself is defective or the Webmaster has not set up the URL redirection correctly.

Fixing 301 errors - CheckUpDown

Redirection of URLs may occur for low-level URLs (specific URLs within the Web site such as www.isp.com/products/index.html) when you reorganise the web site, but is relatively uncommon for top-level URLs (such as www.isp.com) which most users specify for their CheckUpDown accounts. So this error should be fairly infrequent.

The 301 response from the Web server should always include an alternative URL to which redirection should occur. If it does, CheckUpDown automatically tries the alternative URL. This in turn may possibly lead to another redirection which CheckUpDown then tries. This continues for a maximum of 5 redirections. As soon as 5 redirections have occurred, CheckUpDown gives up and reports the 301 error for your account. So you should only ever see the 301 error if 1) the Web server gives no alternative URL on the 301 response or 2) the number of redirections exceeds 5. This second condition should be fairly unlikely - and may indicate a recursive pattern e.g. URL A redirects to URL B which in turn redirects back to URL A.

You first need to check that the IP name we use to check for your account is accurate. If you or your ISP have configured something so that any access using this name should now be permanently redirected to another name, then you need to update your CheckUpDown account to start using the new name.

If you believe that the IP name we use is exact (should not be redirected), please try accessing the current URL using a Web browser. Note carefully which URL actually gets displayed, because your browser may silently switch to a substitute URL if it receives an 301 message from the Web server. If you see any evidence of a new URL, try accessing that directly from your browser. If this works (you see the Web site as expected), then this new URL is what you may need to update on your CheckUpDown account.

If none of the above help, we can analyse the underlying HTTP data streams we receive from the Web server. These can provide additional information about the new URL(s) which the Web server thinks we should be accessing. Before doing this, we prefer you to identify any deliberate changes on your side, liaising with your ISP if needs be.

301 errors should occur infrequently, because top-level URLs do not change often. If they do change, then this is typically because a redirection URL is being suggested. This pervasive change is unlikely to occur by accident, so most often this error can be resolved by updating your CheckUpDown account following a deliberate change of URL on your part.

 


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