When you browse the Internet, you may receive error messages if there is a problem with the website that you are visiting. The problem may be temporary. Therefore, you might want to try to use the website later. If the problem continues, you can try to contact the administrators of the website to ask them to fix the problem.
This article is intended to help website administrators understand what these error messages mean and obtain information about how to fix problems.
Home users: This article is intended for use by support agents and IT professionals. If you're looking for more information about website error messages, please visit the following Windows website:
When website visitors try to access content on a server that is running Microsoft Internet Information Services (IIS) 5.0 and 6.0 through HTTP or File Transfer Protocol (FTP), IIS returns a numeric code that indicates whether the attempt was successful. This status code is recorded in the IIS log, and it may also be displayed in the Web browser or FTP client. The status code can also indicate the exact reason why a request is unsuccessful.
IIS administrators can customize the error message that is displayed to users in their web browser when a request is unsuccessful. For more information about how to create custom HTTP error messages in IIS, click the following article numbers to go to the articles in the Microsoft Knowledge Base:
302570 How to configure custom error messaging for your Web site in IIS
Log File Locations
By default, IIS stores its log files in the following location:
This directory contains separate directories for each World Wide Web (WWW) and FTP site. By default, logs are created daily in the directories and are named by using the date (for example, exYYMMDD.log). For more information about how to set up logging, click the following article number to go to the article in the Microsoft Knowledge Base:
313437 How to enable logging in Internet Information Services (IIS)
1xx - Informational
These status codes indicate a provisional response. The client should be prepared to receive one or more 1xx responses before receiving a regular response.
100 - Continue.
101 - Switching protocols.
2xx - Success
This class of status codes indicates that the server successfully accepted the client request.
200 - OK. The client request has succeeded.
201 - Created.
202 - Accepted.
203 - Non-authoritative information.
204 - No content.
205 - Reset content.
206 - Partial content.
207 - Multi-Status (WebDav).
3xx - Redirection
The client browser must take more action to fulfill the request. For example, the browser may have to request a different page on the server or repeat the request by using a proxy server.
301 - Moved Permanently
302 - Object moved.
304 - Not modified.
307 - Temporary redirect.
4xx - Client Error
An error occurs, and the client appears to be at fault. For example, the client may request a page that does not exist, or the client may not provide valid authentication information.
400 - Bad request.
401 - Access denied. IIS defines several different 401 errors that indicate a more specific cause of the error. These specific error codes are displayed in the browser but are not displayed in the IIS log:
401.1 - Logon failed.
401.2 - Logon failed due to server configuration.
401.3 - Unauthorized due to ACL on resource.
401.4 - Authorization failed by filter.
401.5 - Authorization failed by ISAPI/CGI application.
401.7 – Access denied by URL authorization policy on the Web server. This error code is specific to IIS 6.0.
403 - Forbidden. IIS defines several different 403 errors that indicate a more specific cause of the error:
403.1 - Execute access forbidden.
403.2 - Read access forbidden.
403.3 - Write access forbidden.
403.4 - SSL required.
403.5 - SSL 128 required.
403.6 - IP address rejected.
403.7 - Client certificate required.
403.8 - Site access denied.
403.9 - Too many users.
403.10 - Invalid configuration.
403.11 - Password change.
403.12 - Mapper denied access.
403.13 - Client certificate revoked.
403.14 - Directory listing denied.
403.15 - Client Access Licenses exceeded.
403.16 - Client certificate is untrusted of invalid.
403.17 - Client certificate has expired or is not valid.
403.18 - Cannot execute requested URL in the current application pool. This error code is specific to IIS 6.0.
403.19 - Cannot execute CGIs for the client in this application pool. This error code is specific to IIS 6.0.
403.20 - Passport logon failed. This error code is specific to IIS 6.0.
404 - Not found.
404.0 - (None) – File or directory not found.
404.1 - Web site not accessible on the requested port.
404.2 - Web service extension lockdown policy prevents this request.
404.3 - MIME map policy prevents this request.
405 - HTTP verb used to access this page is not allowed (method not allowed.)
406 - Client browser does not accept the MIME type of the requested page.
407 - Proxy authentication required.
412 - Precondition failed.
413 – Request entity too large.
414 - Request-URI too long.
415 – Unsupported media type.
416 – Requested range not satisfiable.
417 – Execution failed.
423 – Locked error.
5xx - Server Error
The server cannot complete the request because it encounters an error.
500 - Internal server error.
500.12 - Application is busy restarting on the Web server.
500.13 - Web server is too busy.
500.15 - Direct requests for Global.asa are not allowed.
500.16 – UNC authorization credentials incorrect. This error code is specific to IIS 6.0.
500.18 – URL authorization store cannot be opened. This error code is specific to IIS 6.0.
500.19 - Data for this file is configured improperly in the metabase.
500.100 - Internal ASP error.
501 - Header values specify a configuration that is not implemented.
502 - Web server received an invalid response while acting as a gateway or proxy.
502.1 - CGI application timeout.
502.2 - Error in CGI application.
503 - Service unavailable. This error code is specific to IIS 6.0.
504 - Gateway timeout.
505 - HTTP version not supported.
IIS HTTP status codes and their causes
200 - Success. This status code indicates that IIS has successfully processed the request.
206 - Partial Content. This indicates that a file has been partially downloaded. It can enable resuming of interrupted downloads, or split a download into multiple concurrent streams.
207 - Multi-Status (WebDav). This comes before an XML message that can contain several separate response codes, depending on how many sub-requests were made.
301 - Moved Permanently. This and all future requests should be directed to the given URI.
302 - Found. This is frequently represented as “Object Moved” for forms based authentication. The requested resource resides temporarily under a different URI. Because the redirection might be altered occasionally, the client should continue to use the Request-URI for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.
304 - Not Modified. The client requests a document that is already in its cache and the document has not been modified since it was cached. The client uses the cached copy of the document, instead of downloading it from the erver.
401.1 and 401.2 - Logon failed. The logon attempt is unsuccessful because a user name or a password is not valid, or because there is a problem with the system configuration.
401.3 - Unauthorized due to ACL on resource. This indicates a problem with NTFS permissions. This error may occur even if the permissions are correct for the file that you are trying to access. For example, you see this error if the IUSR account does not have access to the C:\Winnt\System32\Inetsrv directory. For more information about how to resolve this problem, click the following article numbers to go to the articles in the Microsoft Knowledge Base:
271071 How to set required NTFS permissions and user rights for an IIS 5.0 Web server
812614 Default permissions and user rights for IIS 6.0
403 - Forbidden. You can receive this generic 403 status code if the Web site has no default document set, and the site is not set to allow Directory Browsing. For more information about how to resolve this problem, click the following article number to go to the article in the Microsoft Knowledge Base:
320051 How to configure the default document in Internet Information Services
403.1 - Execute access forbidden. The following are two common causes of this error message:
You do not have enough Execute permissions. For example, you may receive this error message if you try to access an ASP page in a directory where permissions are set to None, or you try to execute a CGI script in a directory with Scripts Only permissions. To modify the Execute permissions, right-click the directory in Microsoft Management Console (MMC), click Properties, click the Directory tab, and make sure that the Execute Permissions setting is appropriate for the content that you are trying to access.
The script mapping for the file type that you are trying to execute is not set up to recognize the verb that you are using (for example, GET or POST). To verify this, right-click the directory in Microsoft Management Console, click Properties, click the Directory tab, click Configuration, and verify that the script mapping for the appropriate file type is set up to allow the verb that you are using.
403.2 - Read access forbidden. Verify that you have set up IIS to allow Read access to the directory. Also, if you are using a default document, verify that the document exists. For additional information about how to resolve this problem, click the following article number to go to the article in the Microsoft Knowledge Base:
403.3 - Write access forbidden. Verify that the IIS permissions and the NTFS permissions are set up to grant Write access to the directory.For more information about how to resolve this problem, click the following article number to go to the article in the Microsoft Knowledge Base:
403.4 - SSL required. Disable the Require secure channel option, or use HTTPS instead of HTTP to access the page.
403.5 - SSL 128 required. Disable the Require 128-bit encryption option, or use a browser that supports 128-bit encryption to go to the page.
403.6 - IP address rejected. You have configured the server to deny access to your current IP address. For additional information about how to resolve this problem, click the following article number to go to the article in the Microsoft Knowledge Base:
248043 Error Message: 403.6 - Forbidden: IP Address Rejected
403.7 - Client certificate required. You have configured the server to require a certificate for client authentication, but you do not have a valid client certificate installed.
403.8 - Site access denied. You have set up a domain name restriction for the domain that you are using to access the server.For more information about how to resolve this problem, click the following article number to go to the article in the Microsoft Knowledge Base:
248032 Error Message: Forbidden: Site Access Denied 403.8
403.9 - Too many users. The number of users who are connected to the server exceeds the connection limit that you have set. For more information about how to change this limit, click the following article number to go to the article in the Microsoft Knowledge Base:
248074 Error Message: Access Forbidden: Too Many Users Are Connected 403.9
NOTE: Microsoft Windows 2000 Professional and Windows XP Professional automatically impose a 10-connection limit on IIS. You cannot change this limit.
403.12 - Mapper denied access. The page that you want to access requires a client certificate. However, the user ID that is mapped to the client certificate has been denied access to the file. For additional information, click the following article number to go to the article in the Microsoft Knowledge Base:
404 - Not found. This error may occur if the file that you are trying to access has been moved or deleted. It can also occur if you try to access a file that has a restricted file name extension after you install the URLScan tool. You will see “Rejected by URLScan" in the w3svc log files after you install the URLScan tool. In this case, you see "Rejected by URLScan" in the log file entry for that request. For more information, click the following article number to go to the article in the Microsoft Knowledge Base:
248033 How system administrators can troubleshoot an "HTTP 404 - File not found" error message on a server that is running IIS
404.1 – Web Site not accessible on the requested port. This error indicates that the Web site you are trying to access has an IP address that does not accept requests for the port on which this request came.For more information, click the following article number to go to the article in the Microsoft Knowledge Base:
404.2 – Lockdown policy prevents this request. In IIS 6.0, this indicates that the request has been prohibited in the Web Service Extensions list.For more information, click the following article numbers to go to the articles in the Microsoft Knowledge Base:
328419 How to add and remove Web Service Extension files in IIS 6
328505 How to list Web Server Extensions and Extension files in IIS 6.0
328360 How to enable and disable ISAPI extensions and CGI applications in IIS 6.0
404.3 - MIME Map policy prevents this request. This problem occurs if the following conditions are true:
The handler mapping for the requested file name extension is not configured.
The appropriate MIME type is not configured for the Web site or for the application.
405 – Method not allowed. This error can occur when a client sends an HTTP request to the server that is running IIS, and the request contains an HTTP verb that the server does not recognize. To resolve the issue, make sure that the client’s request uses an HTTP verb that is compliant with the HTTP rfc. See the "References" section for information about the HTTP rfc.
500 - Internal server error. You see this error message for many server-side errors. Your event viewer logs may contain more information about why this error occurs. Additionally, you can disable friendly HTTP error messages to receive a detailed description of the error. For more information about how to disable friendly HTTP error messages, click the following article number to go to the article in the Microsoft Knowledge Base:
294807 HOW TO: Disable Internet Explorer 5 'Show Friendly HTTP Error Messages' Feature on the Server Side
500.12 - Application restarting. This indicates that you tried to load an ASP page while IIS was restarting the application. This message should disappear when you refresh the page. If you refresh the page and the message appears again, it may be caused by antivirus software that is scanning your Global.asa file. For additional information, click the following article number to go to the article in the Microsoft Knowledge Base:
500-100.ASP - ASP error. You receive this error message when you try to load an ASP page that has errors in the code. To obtain more specific information about the error, disable friendly HTTP error messages. By default, this error is only enabled on the default Web site.For more information about how to see this error on non-default websites, click the following article number to go to the article in the Microsoft Knowledge Base:
261200 HTTP 500 error message displays instead of ASP error message from 500-100.asp
502 - Bad gateway. You receive this error message when you try to run a CGI script that does not return a valid set of HTTP headers. To resolve the issue, you have to debug the CGI application to determine why it passed invalid HTTP information to IIS.
503 – Service Unavailable. Beginning in IIS 6, the kernel-mode Http.sys component produces an HTTP 503 status. For more information about how to identify and troubleshoot HTTP 503 errors, click the following article number to go to the article in the Microsoft Knowledge Base:
500.19. You receive this error when the XML metabase contains invalid configuration information for the content type that you are trying to access. To resolve this issue, remove or correct the invalid configuration. This problem typically indicates a problem in the ScriptMap metabase key.
1xx - Positive Preliminary Reply
These status codes indicate that an action has started successfully, but the client expects another reply before it continues with a new command.
110 Restart marker reply.
120 Service ready in nnn minutes.
125 Data connection already open; transfer starting.
150 File status okay; about to open data connection.
2xx - Positive Completion Reply
An action has successfully completed. The client can you execute a new command.
200 Command okay.
202 Command not implemented, superfluous at this site.
211 System status, or system help reply.
212 Directory status.
213 File status.
214 Help message.
215 NAME system type, where NAME is an official system name from the list in the Assigned Numbers document.
220 Service ready for new user.
221 Service closing control connection. Logged out if appropriate.
225 Data connection open; no transfer in progress.
226 Closing data connection. Requested file action successful (for example, file transfer or file abort).
227 Entering passive mode (h1,h2,h3,h4,p1,p2).
230 User logged in, proceed.
250 Requested file action okay, completed.
257 "PATHNAME" created.
3xx - Positive Intermediate Reply
The command was successful, but the server needs additional information from the client to complete processing the request.
331 User name okay, need password.
332 Need account for login.
350 Requested file action pending further information.
4xx - Transient Negative Completion Reply
The command was not successful, but the error is temporary. If the client retries the command, it may succeed.
421 Service not available, closing control connection. This may be a reply to any command if the service knows it must shut down.
425 Cannot open data connection.
426 Connection closed; transfer aborted.
450 Requested file action not taken. File unavailable (for example, file busy).
451 Requested action aborted: Local error in processing.
452 Requested action not taken. Insufficient storage space in system.
5xx - Permanent Negative Completion Reply
The command was not successful, and the error is permanent. If the client retries the command, it receives the same error.
500 Syntax error, command unrecognized. This may include errors such as command line too long.
501 Syntax error in parameters or arguments.
502 Command not implemented.
503 Bad sequence of commands.
504 Command not implemented for that parameter.
530 Not logged in.
532 Need account for storing files.
550 Requested action not taken. File unavailable (for example, file not found, no access).
551 Requested action aborted: Page type unknown.
552 Requested file action aborted. Exceeded storage allocation (for current directory or dataset).
553 Requested action not taken. File name not allowed.
Common FTP Status Codes and Their Causes
150 - FTP uses two ports: 21 for sending commands, and 20 for sending data. A status code of 150 indicates that the server is about to open a new connection on port 20 to send some data.
226 - The command opens a data connection on port 20 to perform an action, such as transferring a file. This action successfully completes, and the data connection is closed.
230 - This status code appears after the client sends the correct password. It indicates that the user has successfully logged on.
331 - You see this status code after the client sends a user name. This same status code appears regardless of whether the user name that is provided is a valid account on the system.
426 - The command opens a data connection to perform an action, but that action is canceled, and the data connection is closed.
530 - This status code indicates that the user cannot log on because the user name and password combination is not valid. If you use a user account to log on, you may have mistyped the user name or password, or you may have chosen to allow only Anonymous access. If you log on with the Anonymous account, you may have configured IIS to deny Anonymous access.
550 - The command is not executed because the specified file is not available. For example, this status code occurs when you try to GET a file that does not exist, or when you try to PUT a file in a directory for which you do not have Write access.
Note We strongly recommend that all Web site administrators upgrade to Internet Information Services (IIS) version 7.0 running on Windows Server 2008. IIS 7.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:
If the articles listed here do not help you resolve the problem or if you experience symptoms that differ from those that are described in this article, search the Microsoft Knowledge Base for more information. To search the Microsoft Knowledge Base, visit the following Microsoft Web site: