Exchange 2013 CU7
If you are getting this error on the CAS servers
[Eas] The number of outstanding requests for guard TargetBackend(“servername”) has exceeded the max limit 150. Current request will be rejected.
And this error on the Microsoft Web Application Proxy
The HTTP response from the back end server was not received within the expected interval. Expected interval: 300 seconds.
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Details:
Transaction ID: {f4be1653-43e9-0000-02d0-bef4e943d001}
Session ID: {f4be1653-43e9-0000-02d0-bef4e943d001}
Published Application Name: Exchange Microsoft-Server-ActiveSync
Published Application ID: 9ad23d25-1d98-7a66-3671-6cd7aabcab29
Published Application External URL: https://mailserver.address.com/Microsoft-Server-ActiveSync/
Published Backend URL: https://mailserver.address.com/Microsoft-Server-ActiveSync/
User: <Unknown>
User-Agent: Apple-iPhone5C2/1104.257
Device ID: <Not Applicable>
Token State: NotFound
Cookie State: NotFound
Client Request URL: https://mailserver.address.com/Microsoft-Server-ActiveSync?User=user@address.com&DeviceId=ApplF2LL1VVXDTWF&DeviceType=iPhone&Cmd=Ping
Backend Request URL: https://mailserver.address.com/Microsoft-Server-ActiveSync?User=user@address.com&DeviceId=ApplF2LL1VVXDTWF&DeviceType=iPhone&Cmd=Ping
Preauthentication Flow: PassThrough
Backend Server Authentication Mode: PassThrough
State Machine State: BEBodyWriting
Response Code to Client: <Not Applicable>
Response Message to Client: <Not Applicable>
Client Certificate Issuer: <Not Found>
Try
Reference here
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On all CAS servers:
In \Exchange Server\V15\FrontEnd\HttpProxy\sync\web.config, add this key in the <appSettings> node.
<add key=”HttpProxy.ConcurrencyGuards.TargetBackendLimit” value=”5000″ />
In \Exchange Server\V15\FrontEnd\HttpProxy\rpc\web.config, add this key in the <appSettings> node.
<add key=”HttpProxy.ConcurrencyGuards.TargetBackendLimit” value=”5000″ />
After this change recycle the MSExchangeSyncAppPool and MSExchangeRPCProxyAppPool in IIS manager.
After this, we stopped getting Event ID 2002, and all Connection_Dropped_Event_List_Full stopped appearing in Httperror logs.
