HTTP 449 Retry With (IIS) — What It Means & How to Fix It

Fix Microsoft IIS HTTP 449 Retry With error indicating the server needs additional information from the client to process the request. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: HTTP 449 is a Microsoft extension used by IIS to indicate the request should be retried with additional information. Commonly associated with Exchange Server and WebDAV operations. The response includes a header specifying what additional data the client should provide. This is not an official HTTP status code and is specific to Microsoft server products. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Exchange Server requires additional authentication steps (multi-factor). WebDAV request missing required properties or headers. Request needs to be retried with an extended body or different content type. Server-side extension requires client to acknowledge a condition before proceeding. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Check the response headers for a Ms-WebDAV-RetryWith or similar header indicating what to add. Ensure your client sends all required authentication headers including any MFA tokens. Review Exchange Server or IIS logs for details about the missing information. Update your client to handle 449 by reading the response and retrying with the requested data. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our HTTP Status Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.