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What is this black rectangle with a "do not enter" sign in it? When clicking on it, an empty pull down menu shows.


marked as duplicate by Peter Uithoven, lemonslice, waldyrious, Axel Advento, Lewis Goddard Feb 21 '18 at 10:42

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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    As you see below, this question has been answered already. To avoid flooding the forum with repeat questions, it is always recommended that one searches for the specific issue. It's likely the problem in question has already been resolved. Thanks! – Pretzel Jones Feb 16 '18 at 14:44

It means you are running an application which either has no icon or which is unable to display the icon correctly. Dropbox for example has this problem.

Are you running Dropbox? If so then you can fix it using the solution here: Problems with Dropbox

If it is some other application then there is likely a similar fix needed.

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