Hello,
access to most backend websites on the mailbox server logs asp.net Event ID 1310 A configuration error ocured.

Looking to the web.config file A reference to D:\Exchange\ClientAccess\SharedWebConfig.Config has been found, but this file did not exist on both servers MBX and CAS role. The Installdir has been set to D:\Exchange during Installation wizard. The setup did not log any error creating such a file to C:\ExchangeSetupLogs\ExchangeSetup.log.

Another machine installed with Exchange 2013SP1, then updated to CU7 is OK. \TF

Few of us have memorized all event ID numbers and few of us are inclined to look up the numbers you've posted, so please post the entire event log entry.  You are welcome to use the handy-dandy "copy to clipboard" button in the event log detail window to assist you with this.

Hi,

Are there any error when login OWA or ECP?
As Ed mentioned, please post specific information about your question for further troubleshooting.

Besides, please check to see if there is a SharedWebConfig.Config file in the following directories:
<install drive>\Program Files\Microsoft\Exchange Server\V15\ClientAccess
<install drive>\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy

Also, heres an thread about miss this file in relevant location. For your reference:
https://social.technet.microsoft.com/Forums/office/en-US/6699ad92-701d-4966-b202-90c9be6bf735/exchange-2013-cu6-event-id-1003?forum=exchangesvrgeneral

Thanks