LinkScan Reference Manual

Section 11. LinkScan Status and Error Codes

The following section describes each of the LinkScan Error and Status Codes. They are divided into 6 Severities:

Unknown: LinkScan has not tested or was unable to test this link (probably because it uses a protocol that is not supported by LinkScan).

Error: LinkScan found a hard error on this link.

Possible Error: There may be a problem with this link. It should be retested at a later time.

Warning: LinkScan found something unusual about this link. Manual inspection highly recommended.

Advisory: This link is probably ok, but manual inspection recommended.

No Error: This is a good link.

The Severity associated with any specific Error or Status Code may be customized by the LinkScan Administrator through the use of the Statuscode option.

Status codes in the range 0-99 are generated exclusively by LinkScan and generally refer to the status of local links (HTML files, Non-HTML files, etc.).

Status codes in the range 800-999 are generated exclusively by LinkScan and generally refer to Networking Problems (Failed DNS lookups, failure to connect to a remote server or timeouts) as well as some other LinkScan detected warning or advisory messages.

Status codes in the range 100-599 are defined exclusively by the HyperText Transfer Protocol:

• 2xx status codes generally indicate a successful operation

• 3xx status codes generally apply to redirections where the client (e.g. browser) must take further action before the operation can be successfully completed

• 4xx status codes generally indicate a client error. For example, an invalid or incomplete request

• 5xx status codes generally indicate a server error.

Status codes in the range 600-799 are not currently used.

Status codes of 1000 refer to FTP errors.

No Status (0)

• Explanation: This object has not been tested.
• Action: Inspect this link manually.

HTML File (1)

• Explanation: This HTML document was found OK.
• Action: None required.

Error: Missing HTML File (2)

• Explanation: The Referring Page is linked to an HTML file that does not exist on your server.
• Action: Create/restore the missing file or correct the erroneous reference.

Non-HTML File (3)

• Explanation: This non-HTML file was found OK.
• Action: None required.

Error: Missing non-HTML File (4)

• Explanation: The Referring Page is linked to a non-HTML file that does not exist on your server.
• Action: Create/restore the missing file or correct the erroneous reference.

Anchor (5)

• Explanation: The corresponding <a name=> tag was found OK.
• Action: None required.

Error: Missing Anchor (6)

• Explanation: The Referring Page is linked to a <a name=> tag that does not exist within the target document.
• Action: Create/restore the missing tag or correct the erroneous reference.

Warning: Orphaned HTML File (7)

• Explanation: This HTML file cannot be reached (directly or indirectly) from your home page.
• Action: Check whether this is intentional or an error.

Warning: Orphaned non-HTML File (8)

• Explanation: This non-HTML file cannot be reached (directly or indirectly) from your home page.
• Action: Check whether this is intentional or an error.

Imagemap File (9)

• Explanation: This server-side Imaagemap file was found OK.
• Action: None required.

Error: Missing Imagemap File (10)

• Explanation: The Referring Page is linked to a server side Imagemap file that does not exist on your server.
• Action: Create/restore the missing file or correct the erroneous reference.

Apparently Valid mailto: Link (11)

• Explanation: This mailto: link appears valid based on an examination of the tag and Email address syntax.
• Action: None required.

Possible Error: Apparently Invalid mailto Link (12)

• Explanation: This mailto: link appears invalid based on an examination of the tag and Email address syntax.
• Action: Inspect this link manually.

Warning: Missing / (13)

• Explanation: This link is almost certainly missing a trailing "/". LinkScan was able to validate the link by adding the "/".
• Action: Add a "/" character to the end of the existing URL. This omission, although not normally fatal, may cause visitors that try to follow the link problems or delays.

Warning: Unprocessed SSI (14)

• Explanation: LinkScan identified but did not process this Server Side Include (SSI). Use the Execute command if you want LinkScan to retrieve the referring document via HTTP so that any SSI's are processed by your web server.
• Action: Inspect this Server Side Include manually.

PDF File (15)

• Explanation: This PDF document was found OK.
• Action: None required.

Error: Missing PDF File (16)

• Explanation: The Referring Page is linked to a PDF document that does not exist on your server.
• Action: Create/restore the missing file or correct the erroneous reference.

Continue (100)

• Explanation: This HTTP Status Code will not normally arise with LinkScan.
• Action: Inspect this link manually.

Switching Protocols (101)

• Explanation: This HTTP Status Code will not normally arise with LinkScan.
• Action: Inspect this link manually.

Good URL (200, 201, 202, 203, 205, 206)

• Explanation: LinkScan found a good (external) URL.
• Action: None required.

Error: No Content (204)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Multiple Choices (300)

• Explanation: The target server requires a language selection before serving the applicable document.
• Action: Add a command to the linkscan.cfg file such as:
  Extraheader = Accept-Language: en

Error: Moved Permanently (301)

• Explanation: This URL has moved permanently.
• Action: Update this link as soon as possible. The re-direction instruction may expire shortly, making it harder for you to find the new location.

Advisory: Moved Temporarily (302)

• Explanation: The URL of the page retrieved is different from the URL of the page requested. This is a design feature of the referenced server. According to the http specifications, you should continue using the existing URL. However, in our experience, such links should be inspected manually. Some servers report redirections to temporary URL's that are specific to the current user session. It would clearly be undesirable to modify your existing hyperlinks in these situations. But, other servers return a 302 Status Code when the URL has in fact been moved "permanently".
• Action: Inspect this link manually.

Error: Network or Remote Server (303, 304)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Use Proxy (305)

• Explanation: This link must be accessed via a proxy server.
• Action: Inspect this link manually and contact your LinkScan Administrator.

Error: Network or Remote Server (400)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Warning: Unauthorized (401)

• Explanation: The remote server reported that you are not authorized to access the requested object. You may be able to access it manually if you supply a valid username and password. Also, see the section on Testing Password Protected URL's for additional information.
• Action: Inspect this link manually.

Warning: Payment Required (402)

• Explanation: The remote server reported that you are not authorized to access the requested object. You may be able to access it manually if you supply a valid username and password.
• Action: Inspect this link manually.

Warning: Forbidden (403)

• Explanation: The remote server understood the request but refused to fulfill it. Supplying a username and password will not help.
• Action: Inspect this link manually.

Error: Not Found (404)

• Explanation: The remote server reported that the requested object does not exist. This condition is probably (but not necessarily) permanent.
• Action: Inspect the link manually. A very small number of servers report a "Not Found" error when there is, in fact, no problem. In some cases, the server may display a "Moved" message even though it did not supply a "Moved" header.

Error: Method Not Allowed (405)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Not Acceptable (406)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Proxy Authentication Required (407)

• Explanation: The Proxy Server requires authentication.
• Action: Review the LinkScan Proxy Server configuration settings or contact your LinkScan Administrator. See Proxy Servers.

Possible Error: Request Timed Out (408)

• Explanation: The Request timed out.
• Action: Use the -retest feature or check the link manually. This URL is currently unavailable. LinkScan was not able to establish whether the situation is temporary or permanent. You may wish to probe the site using the Unix ping and traceroute utilities.

Error: Conflict (409)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Gone (410)

• Explanation: The remote server reported that the requested object does not exist. The condition is permanent and no forwarding address is known.
• Action: Inspect the link manually.

Error: Length Required (411)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Precondition Failed (412)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Request Entity Too Large (413)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Request URI Too Large (414)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Error: Unsupported Media Type (415)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Possible Error: Internal Server Error (500)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Possible Error: Not Implemented (501)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Possible Error: Bad Gateway (502)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Possible Error: Service Unavailable (503)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Possible Error: Gateway Timed Out (504)

• Explanation: The connection to the remote server timed out.
• Action: Use the -retest feature or check the link manually. This URL is currently unavailable. LinkScan was not able to establish whether the situation is temporary or permanent. You may wish to probe the site using the Unix ping and traceroute utilities.

Possible Error: HTTP Version Not Supported (505)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Possible Error: Network or Remote Server (600, 601, 602, 603)

• Explanation: An unusual error occurred.
• Action: Inspect this link manually.

Advisory: URL Skipped - Recently Tested (800)

• Explanation: This link was skipped because it has been tested recently. See Controlling Excessively Frequent Testing.
• Action: None required.

Possible Error: URL Skipped - Bad Server (801)

• Explanation: This link was skipped because an excessive number of other links to the same server appeared broken. The server is probably down, either temporarily or permanently. See Controlling Excessively Frequent Testing.
• Action: Retest this link later and/or manually inspect the links to this server.

Advisory: URL Skipped - FTP Limit (802)

• Explanation: This link was skipped because the limit on the number of FTP links to any one server was exceeded. See Controlling Excessively Frequent Testing.
• Action: Manually inspect this link and/or increase the Maxftp setting.

Advisory: URL Skipped - CGI Limit (803)

• Explanation: This link was skipped because the limit on the number times LinkScan checks the same CGI with different queries was exceeded. This avoids the possibility of LinkScan checking the same URL with a potentially infinite number of automatically generated query strings. See Controlling Excessively Frequent Testing.
• Action: Manually inspect this link and/or increase the Maxcgi setting.

Possible Error: Server Not Found - No DNS Entry (900)

• Explanation: LinkScan was unable to locate the requested server.
• Action: Use the -retest option or check the link manually. This server may no longer exist. Or, it is possible that the remote site's Domain Name Server (DNS) was temporarily unavailable at the time LinkScan tried to access it. You may wish to probe the site using the Unix nslookup utility.

Possible Error: DNS Error or Timeout (901)

• Explanation: LinkScan was unable to complete a DNS lookup.
• Action: Use the -retest feature or check the link manually. This URL is currently unavailable. LinkScan was not able to establish whether the situation is temporary or permanent. You may wish to probe the site using the Unix ping and traceroute utilities.

Possible Error: Failed to Connect (902)

• Explanation: LinkScan was unable to establish a TCP/IP connection to the remote server.
• Action: Use the -retest feature or check the link manually. This URL is currently unavailable. LinkScan was not able to establish whether the situation is temporary or permanent. You may wish to probe the site using the Unix ping and traceroute utilities.

Possible Error: Timed Out (903)

• Explanation: The connection to the remote server timed out.
• Action: Use the -retest feature or check the link manually. This URL is currently unavailable. LinkScan was not able to establish whether the situation is temporary or permanent. You may wish to probe the site using the Unix ping and traceroute utilities.

Warning: Missing / (904)

• Explanation: This link is almost certainly missing a trailing "/". LinkScan was able to validate the link by adding the "/".
• Action: Add a "/" character to the end of the existing URL. This omission, although not normally fatal, may cause visitors that try to follow the link problems or delays.

Warning: Invalid Response but Probably OK (905)

• Explanation: The remote server did not supply a valid http header, but it did appear to serve up a valid HTML document.
• Action: Inspect this link manually.

Warning: URL Contains an IP Address (906)

• Explanation: This link uses a numeric IP address. These addresses are much more likely to change than conventional server addresses referenced via the Domain Name Service (DNS).
• Action: We recommend that you use a conventional URL if at all possible.

Error: Multiple Redirections (907)

• Explanation: This URL appeared to be subject to multiple redirections.
• Action: We recommend that you inspect your server redirections (often defined in a .htaccess file).

Warning: Missing / (908)

• Explanation: This link is almost certainly missing a trailing "/". LinkScan was able to validate the link by adding the "/".
• Action: Add a "/" character to the end of the existing URL. This omission may cause significant problems for some users that access the web via proxy servers.

Error: Disconnected (909)

• Explanation: This error typically results when a remote server disconnects a TCP/IP connection prematurely.
• Action: Inspect this link manually. If problems persist, please contact LinkScan Technical Support at linkscan@elsop.com.

Warning: Location Header Not Absolute (910)

• Explanation: The server attempted to redirect the request to a different URL using an HTTP "Location" header but failed to supply an absolute URL as required by the HTTP specifications.
• Action: Check the HTTP server configuration files and/or any CGI scripts that generate HTTP "Location" headers and ensure they transmit an absolute URL on redirections.

Error: URL Contains Unsafe Character (911)

• Explanation: This link contains an 'unsafe' character; probably a control character or a non-encoded space (spaces in URL's should be written as "%20"). Different browsers will interpret this link differently.
• Action: We recommend that you inspect and correct this link.

Advisory: SSL Server Connected - Path Not Checked (912)

• Explanation: LinkScan was able to establish a TCP/IP connection to the specified port (Default: 443) on the specified server. LinkScan does not natively support SSL/HTTPS and did not validate the pathname portion of the URL.
• Action: We recommend that you inspect this link manually using a browser with SSL support if you wish to validate the complete URL.

Advisory: Simulated Redirect (913)

• Explanation: LinkScan processed a Redirect directive in the linkscan.cfg file.
• Action: Check this link manually.

Warning: Meta Redirect (914)

• Explanation: LinkScan detected a redirection specified using a <META HTTP-EQUIV REFRESH> tag.
• Action: This construct is not supported by all clients. We recommend that you at least insert a regular hyperlink in this document that will be visible by someone viewing the page.

Warning: Meta Location not Absolute (915)

• Explanation: LinkScan detected a redirection specified using a <META HTTP-EQUIV REFRESH> tag. Furthermore, the target location was specified using a relative URL.
• Action: This construct is not supported by all clients. We recommend that you specify the REFRESH using an Absolute URL and insert a regular hyperlink in this document that will be visible by someone viewing the page.

Error: Could not Create Socket (990)

• Explanation: LinkScan was not able to create a socket (network connection) while testing this link. This indicates an internal problem with LinkScan and/or your operating system.
• Action: Contact LinkScan Technical Support at linkscan@elsop.com.

Error: Unknown (999)

• Explanation: LinkScan was not able to establish the status of this link. This error tends to arise with approximately 0.1 percent of servers on the Web. Generally, the remote server is completely non-compliant with the http specifications or refused to accept TCP/IP connections from your current IP address.
• Action: Inspect this link manually.

Error: FTP: (1000)

• Explanation: LinkScan failed to receive a satisfactory response from this FTP server. The error description reflects the actual message returned by the FTP server.
• Action: Inspect this link manually.

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Updated: November 28, 1999