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Exchange 2010: Unable to Browse OWA and ECP with HTTP Error 404

Today I got this issue while working for a critical client.

Well. This is a simple issue but there is no relevant article or blog available so I am posting. Many blogs are talking about replacing applicationhost.config file from backup. I would not recommend to follow it unless you are aware the backup is new and there is relevant change was down after this. Old backup can change your current configuration.



2 CAS/Hub Transport servers.

2 DC

2 mailbox role in DAG


I was configuring Windows NLB for them.



After Configuring WNLB one CAS server was unable to browse OWA/ECP and giving the following error.

‘HTTP Error 404. The requested resource is not found.’




Default website was stopped for some reason and this is not normal so you would not think of this and troubleshoot IIS.

Started default website and OWA/ECP started working.



Stick to the basics.


Prabhat Nigam

Microsoft MVP | Exchange Server




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