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ErrorServerBusy response code when you synchronize an EWS-based application to a mailbox in an Exchange Server 2010 environment

View products that this article applies to.

Symptoms

When you try to synchronize an Exchange Web Service (EWS)-based application to a mailbox in a Microsoft Exchange Server 2010 environment, you receive an ErrorServerBusy response code and an error message that resembles the following:
The server cannot service this request right now. Try again later.

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Cause

This issue occurs because the EWS monitoring detects that the limit for the requests that are from a Client Access server to a Mailbox server was reached. Therefore, the Client Access server returns an ErrorServerBusy response code to all EWS requests to the Mailbox server.

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Resolution

To resolve this issue, install Exchange Server 2010 Service Pack 3 (SP3) on the Exchange Server 2010 servers. For more information about Exchange Server 2010 SP3, click the following article number to view the article in the Microsoft Knowledge Base:

2808208 Description of Exchange Server 2010 SP3

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Workaround

To work around this issue, make the following changes in the Web.config file on the Client Access server:
  1. Find the following code in the Web.config file:
    <add key="MbxServerEnableConcurrencyControl" value="true" />
    Change the MbxServerEnableConcurrencyControl value from true to false.
  2. Add the following line of code into the Web.config file:
    <add key="MdbFairUnhealthyLatencyThreshold" value="500" />
Note The Web.Config file is located in the following path:
Drive\Program Files\Microsoft\Exchange Server\V14\ClientAccess\exchweb\ews

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Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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More Information

For more information about the ErrorServerBusy response code, go to the following Microsoft website:
General information about response codes

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Keywords: kbqfe, kbfix, kbexpertiseinter, kbsurveynew, kb

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Article Info
Article ID : 2800080
Revision : 1
Created on : 1/7/2017
Published on : 2/12/2013
Exists online : False
Views : 340