I just updated our test server from version 4.4.4 to version 5 and one of my colleagues got this error… any suggestion? I cannot do the rollback to version 4.2.x 
Regards,
Alberto
If you go to Admin->Tools->System configuration what do you have for HomepageComponents config?
HomepageComponents
[
‘QuickCreate’,
‘Quicksearch’,
‘MyCalendar’,
‘MyAdminQueues’,
‘MySupportQueues’,
‘MyReminders’,
‘RefreshHomepage’
]
site config
If it is just one user getting this, get them to edit their home page. It could be that they added a couple of portlets you no longer have.