If it is a rokuTV(not separate roku device) and it does this on every app and not some, then I would manually install the update again and restart the system manually.
SETTINGS, SYSTEM, SYSTEM UPDATE, CHECK NOW
then after message screen...
SETTINGS, SYSTEM, POWER, SYSTEM RESTART
Also make sure you are actually connected to network, sometimes wifi will drop off the tvs for some reason as opposed to their roku devices. Happens quite a bit on my Insignia RokuTV but not my sticks or boxes.
SETTINGS, NETWORK, ABOUT (or CHECK CONNECTION).
See if that works for you. For ordinary user, thats the extent of it. There are other ways to install previous updates but not easily and not "roku recommended".