Status Code Handling with Web.Contents

The Web.Contents function has some built-in functionality for dealing with certain HTTP status codes. The default behavior can be overridden in your extension using the ManualStatusHandling field in the options record.

Automatic retry

Web.Contents will automatically retry requests that fail with one of the following status codes:

Code	Status
408	Request Timeout
429	Too Many Requests
503	Service Unavailable
504	Gateway Timeout
509	Bandwidth Limit Exceeded

Requests will be retried up to three times before failing. The engine uses an exponential back-off algorithm to determine how long to wait until the next retry, unless the response contains a Retry-after header. When the header is found, the engine will wait the specified number of seconds before the next retry. The minimum supported wait time is 0.5 seconds, and the maximum value is 120 seconds.

Note

The Retry-after value must be in the delta-seconds format. The HTTP-date format is currently not supported.

Authentication exceptions

The following status codes will result in a credentials exception, causing an authentication prompt asking the user to provide credentials (or sign in again in the case of an expired OAuth token).

Code	Status
401	Unauthorized
403	Forbidden

Note

Extensions are able to use the ManualStatusHandling option with status codes 401 and 403, which is not something that can be done in Web.Contents calls made outside of a custom data connector (that is, directly from Power Query).

Redirection

The following status codes will result in an automatic redirect to the URI specified in the Location header. A missing Location header will result in an error.

Code	Status
300	Multiple Choices
301	Moved Permanently
302	Found
303	See Other
307	Temporary Redirect

Note

Only status code 307 will keep a POST request method. All other redirect status codes will result in a switch to GET.