When installing a Rollup, I recommend you use the same account that
you used to install Exchange Server. If you are using a different
account, that account needs to have Local Administrator rights as well
as rights to read Active Directory on Exchange object as well as
server level (as the update needs to determine which roles are
installed on the server). Not having required permissions can lead to
OWA not being updated correctly and displaying a blank page after
update has completed.

If you have modified the logon.aspx file, it will not be patched by
the Update Rollup installer. As a result Outlook Web Access may not be
updated correctly and it may display a blank page after the update has
finished. In order to avoid this problem, rename the logon.aspx file
before applying the update rollup. After you apply an update rollup
package, you must re-create Outlook Web Access customization in