A "coup attempt" is any serious effort by a small group to forcibly seize part or all of the national government of Ukraine. This question resolves YES regardless of whether the coup attempt succeeds, and NO if no coup attempt occurs and 2024 is over.
credible evidence of a coup plot alone would not count (fails the "serious" requirement)
demonstrations calling for the government to resign would not count (fails the "forcible" requirement, fails the "small group" requirement)
the assassination of Zelensky, even by Ukrainian actors, would not count as a coup attempt unless paired with other actions that are typical of an effort to seize state power, e.g. capturing strategic buildings in Kyiv
the forcible seizure of a sub-national government would not count (fails the "national" requirement)
the Wagner rebellion, had it happened in Ukraine, would have counted