In plasma 4, when running apt-get update/upgrade in terminal the system tray notifications would show the appropriate state in accordance with the apt-get results - a notification would appear when new updates were available when running apt-get update, and the notification would disappear when running apt-get upgrade to install them. In plasma 5, running apt-get update does cause the update notification to appear if there are updates available, however after running apt-get upgrade to install them, the notification remains, claiming there are still updates available. An additional apt-get update+upgrade confirms that this is not the case. The updates notification should remain in sync with the true state of updates, even when apt-get is being run from the terminal. Reproducible: Always
*** This bug has been marked as a duplicate of bug 346622 ***
I don't know how it's related technically to bug #346622, but at least as far as the symptoms are described, they are not the same. That one sounds like it's about the updates notification popping up after it's been dismissed (but no update actually performed?), whereas this one is for the notification still showing after the update has actually completed via apt-get and there are no more updates available. If this is technically the same bug then just ignore this comment, but if it's not really the same bug, this should be reopened.