Hello,

I've spent the past 7 hours trying to figure out why Office Web App Server will not work correctly with my Sharepoint Server  (2013). When ever I try to open or edit a document via web app it keeps giving me the Sorry there was a problem and we can't open this document. I know the Office Web App Server was set up correctly, gave me the xml file and pluse I tied it into exhange and it works just dandy with it. I have unbounded the server four times and re bound it and made sure that I ran Set-SPWOPIZone command for external and https. I have added the domain to the Trusted list on the Wac Server. I have also made sure that the AllowOAuthOverHttp was false. I have no clue what to do any more it works with lync and exchange. I'm sure I'm not the only person who has ran into this problem lol. 

Hi

please provide more details from logs fileAlso please check this similar post

https://social.technet.microsoft.com/Forums/sharepoint/en-US/fdbf2198-5a62-422a-9015-a65599eabeb5/office-web-apps-2013-sorry-there-was-a-problem-and-we-cant-open-this-document-if-this-happens?forum=sharepointadmin

The service application has an account used as its identity.  This account has to have dbowner rights on the content database where office web apps will be used.  Have you checked this?