When you are trying to configure office web apps in SharePoint 2013, you may face the issue like" Sorry, there was a problem and we can’t open this document. If this happens again, try opening the document in Microsoft Word.”
In order to resolve the problem, run the following powershell commands.
$config = (Get-SPSecurityTokenServiceConfig)
$config.AllowOAuthOverHttp = $true
$config.Update()