I have just trying to upgrade to the latest version from V1.7.4 to V1.9.6 of nextgen gallery.
It requires a database upgrade so I clicked on the "upgrade now..." link. It turns red and nothing happens. My browser does not indicate anything is loading and the page doesn't change.
I left it for a few minutes and tried again. Nothing. Tried refreshing, deactivating/reactivating plugin all to no avail.
I can't edit any settings or galleries until the db is upgraded.