B.5 Server Failure Status Codes

The range of status codes from 500 to 599 indicates that some error occurred on the server. It may be a temporary condition, but more often it's fairly permanent.

B.5.1 500 Internal Server Error

500 Internal Server Error is often a server coding error. A WebDAV server implemented in C might include "asserts" for conditions that the programmer believes should not occur. Code that deals with unexpected asserts or exceptions should usually construct a 500 Internal Server Error response and send it to the client as part of the cleanup.

Defined in HTTP/1.1.

B.5.2 501 Not Implemented

501 Not Implemented means that the server does not support the method used. For example, a LOCK request to a server that only implements WebDAV Level 1 should result in a 501 Not Implemented response. Similarly, a typo or case mismatch in the method name (e.g., "PROPATCH" for "PROPPATCH") would result in this response.

Defined in HTTP/1.1.

B.5.3 502 Bad Gateway

502 Bad Gateway is most frequently returned by a proxy that fails to reach the destination Web server at all and can't complete the request.

It's possible that a destination Web server could return this status code, too. A client could send a COPY request with a Destination header naming a target on another server. Since WebDAV doesn't support copying a file to another server, the appropriate response might be 502 Bad Gateway. Even within what appears to be a single repository (a namespace exposed through a single consistent domain name), there may be clustering or multiple database backends, and imperfect reliability in integrating these components may sometimes result in a 502 Bad Gateway error.

Defined in HTTP/1.1.

B.5.4 503 Service Unavailable

This code is returned when the server is temporarily unavailable to handle requests. This could happen when the server is being reconfigured, upgraded, or is simply too busy.

Defined in HTTP/1.1.

B.5.5 504 Gateway Timeout

This response code indicates that the responding server was able to contact another Web server to complete the request, but that other Web server took too long to finish. Like 502 Bad Gateway, this would frequently be used by Web proxy servers that timeout in their requests to destination Web servers.

Defined in HTTP/1.1.

B.5.6 505 HTTP Version Not Supported

The server does not support the HTTP version of the request.

Defined in HTTP/1.1.

B.5.7 507 Insufficient Storage

507 Insufficient Storage response code is used to indicate that the server has run out of memory or persistent storage. It can also be used to indicate that the user has some kind of quota that has been reached.

Defined in WebDAV.