If you get timeout errors with Exchange accounts on iPhone, iPad, or iPod touch

A client's ActiveSync requests might create a series of HTTP 500 errors. These errors might make the Exchange email, calendar, or contact data on an iOS device reload. If you're an administrator, learn how to fix this for your devices.

This article is intended for an Exchange Server administrator. If you get connection timeout errors on your iPhone, iPad, or iPod touch, contact your company's Exchange Server administrator.

An iPhone, iPad, or iPod touch might get connection errors from an intermediate server. These errors happen if a transaction times out before the Mailbox server and device finish a session. Sometimes, a Time to Live (TTL) or heartbeat interval (HBI) on the intermediate servers is shorter than the life of the Exchange ActiveSync transactions. When this happens, the device and the Mailbox server don't communicate.

Check the TTL settings for the intermediate servers between the iOS devices and the Mailbox server. ActiveSync transactions fail when these settings don't exceed the maximum TTL.

Identify the error

When the transaction takes longer than the TTL settings allow, an error appears on the device. It might be an HTTP 500 error or a Status error 110. These errors might make the account data in that folder reload. For example, requests to sync an Exchange Calendar might result in a series of 500 errors in a row. When this happens, iOS asks Exchange to send all calendar data the next time it connects. This lets iOS replace its local cache of calendar data.

Check the ActiveSync log to find out what type of error made the data reload. Here's an example of an HTTP 500 error in an ActiveSync log:

Event Type: Error
Event Source: Server ActiveSync
Computer: Server

Description: Unexpected Exchange mailbox Server error: Server: [myserver.company.com] User: [user@company.com] HTTP status code: [500]. Verify that the Exchange mailbox Server is working correctly.

Learn how to identify the HTTP or Status errors in your Exchange logs.

Set the server's HBI to 59 minutes

The HBI is the amount of time that iOS calculates should pass between pings to the server. If you're the Exchange Server administrator, set the server's HBI to 59 minutes. Learn how to adjust the HBI for your server.

Confirm the timeout for all network firewalls

If you're the system or network administrator, set all network firewalls to time out at 30 minutes or more. The default timeout for some devices might be as low as five minutes. Give the pings and other sync processes enough time to travel to the mailbox and back. Learn how to set and confirm all network firewall settings.

Update the iPhone, iPad, or iPod touch settings

To decrease the amount of data that syncs to the device, lower these settings:

  • The number of Mail Days to Sync
  • The Sync Calendar Events timeframe
  • How often the device fetches data from the server, and how often the server pushes data to the device

This document will be updated as more information becomes available.

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