Outlook web app out of date problem

Hello experts,

We have an Exchange 2010 SP2 and Exchange 2003 SP2 in our single domain organisation.

It was working well, but after a power failure emails stopped working. If I try to login through OWA, I receive this error: 

The Outlook Web App address https://mail.ourdomain.com/owa is out of date.

I googled for this error and found it's related to some 365 integration config. In fact we don't have 365. 

I found also that some people are talking about a certificate issue. Actually the server is still new and the self signed certificate expires in 2018.

Any help?