After you install update rollup 1,2 or 3 on an Exchange 2010 Client Access Server you often get a blank OWA page when browsing to the OWA page.

After installing the rollup updates you will receive something like the following URL; .

To fix this issue you must start updatecas.ps1 in the Exchange Management Shell. You can find the script in C:\Program Files\Microsoft\Exchange Server\V14\Bin . The script updatecas.ps1 will handle the OWA and ECP updates. The updatecas script comes with the update rollup.