While trying to access the Exchange Control Panel (https://exchangeserver/ecp), I kept getting the following error:

“Sorry! We’re having trouble processing your request right now. Please try again in a few minutes.”

Outlook Web Access (https://exchangeserver/owa) worked fine.

Thanks to jhoskins for the following post that provided the solution:

As mentioned in the post, I was also running Exchange 2010 on Windows 2012 server.

Since OWA was working, it just a matter of getting the ECP Application Pool in IIS to use the same version of .Net Framework. When the ECP was not working, the MSExchangeECPAppPool Application Pool was set to use version 4.0.30319. I simply changed it to version 2.0.50727 like the MSExchangeOWAAppPool was set, and it started working fine.