When configuring Office Web Apps for your local development environment, you may run into the following error:
“Sorry, there was a problem and we can’t open this document. If this happens again, try opening the document in Microsoft Word.”
This error is probably caused by overlooking Step 5 in the TechNet article: http://technet.microsoft.com/en-us/library/ff431687.aspx:
On your SharePoint 2013 Server, run the following in your management shell:
$config = (Get-SPSecurityTokenServiceConfig)
$config.AllowOAuthOverHttp = $true
And it should resolve your problem!