OAB not Working

Question

Hi,
I installed the new Exchange 2013 on 2 servers, with DAG.
Everything seems to be working except for OAB.
Outlook is eternally downloading the address book.
If I try to open the site locally on the server I get the following error:
System.Configuration.ConfigurationErrorsException: Microsoft.Exchange.HttpProxy.ProxyModule,Microsoft.Exchange.FrontEndHttpProxy does not implement
IHttpHandlerFactory or IHttpHandler.
I already looked on the internet for this error but couldn't find anything related to exchange.
I also checked OAB folder and the only files inside are the global.asax and web.config. 
I also see in the event viewer the errors below repeating over and over.
Any idea what could be the issue or how can I troubleshoot this or reset OAB configuration to default?
Thanks in advance.
Event 1003, MSExchange Front End HTTP Proxy
[Oab] An internal server error occurred. The unhandled exception was: System.Configuration.ConfigurationErrorsException: Microsoft.Exchange.HttpProxy.ProxyModule,Microsoft.Exchange.FrontEndHttpProxy does not implement IHttpHandlerFactory or IHttpHandler.
   at System.Web.Configuration.HandlerFactoryCache.GetHandlerType(String type)
   at System.Web.Configuration.HandlerFactoryCache..ctor(String type)
   at System.Web.HttpApplication.GetFactory(String type)
   at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Event 4999, MSExchange Common 
Watson report about to be sent for process id: 16868, with parameters: E12IIS, c-RTL-AMD64, 15.00.0712.022, w3wp#MSExchangeOABAppPool, System.Web, S.W.C.HandlerFactoryCache.GetHandlerType, S.Configuration.ConfigurationErrorsException, e0bc, 04.00.30319.18045.
ErrorReportingEnabled: True
Event 1310, ASP.NET 4.0.30319.0 
Event code: 3008 
Event message: A configuration error has occurred. 
Event time: 28/07/2013 11:22:03 
Event time (UTC): 28/07/2013 10:22:03 
Event ID: b65c0349ff7a4f7e83382f8760c0d4fa 
Event sequence: 37858 
Event occurrence: 12620 
Event detail code: 0 
Application information: 
    Application domain: /LM/W3SVC/1/ROOT/OAB-1-130190356614067522 
    Trust level: Full 
    Application Virtual Path: /OAB 
    Application Path: C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\OAB\ 
    Machine name: EXCH2012A 
Process information: 
    Process ID: 16868 
    Process name: w3wp.exe 
    Account name: NT AUTHORITY\SYSTEM 
Exception information: 
    Exception type: ConfigurationErrorsException 
    Exception message: Microsoft.Exchange.HttpProxy.ProxyModule,Microsoft.Exchange.FrontEndHttpProxy does not implement IHttpHandlerFactory or IHttpHandler.
   at System.Web.Configuration.HandlerFactoryCache.GetHandlerType(String type)
   at System.Web.Configuration.HandlerFactoryCache..ctor(String type)
   at System.Web.HttpApplication.GetFactory(String type)
   at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Request information: 
    Request URL: https://localhost:443/OAB/ 
    Request path: /OAB/ 
    User host address: 127.0.0.1 
    User:  
    Is authenticated: False 
    Authentication Type:  
    Thread account name: NT AUTHORITY\SYSTEM 
Thread information: 
    Thread ID: 43 
    Thread account name: NT AUTHORITY\SYSTEM 
    Is impersonating: False 
    Stack trace:    at System.Web.Configuration.HandlerFactoryCache.GetHandlerType(String type)
   at System.Web.Configuration.HandlerFactoryCache..ctor(String type)
   at System.Web.HttpApplication.GetFactory(String type)
   at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Custom event details: 

Answer 1

For the "owa" virtual directory
Open Exchange Management Shell (EMS), and then run the following cmdlet to change the authentication method of the "owa" virtual directory to Windows authentication:
set-Owavirtualdirectory -identity "E15MBX\owa (Exchange Back End)" -WindowsAuthentication $True -Basicauthentication $false -Formsauthentication $false
Run the following command on both the Client Access and Mailbox servers to restart Internet Information Services (IIS):
iisreset /noforce
For the "ECP" virtual directory
Start Windows PowerShell.
Type the following commands, and then press Enter after each line:
Add-PSSnapin *exchange*
Set-EcpVirtualDirectory -Identity "E15MBX\ecp (Exchange Back End)" -WindowsAuthentication $true -FormsAuthentication $false
Run the following command on both the Client Access and Mailbox servers to restart Internet Information Services (IIS):
iisreset /noforce
Dinesh S.