Collaborative cloud platforms make it easier and more convenient for multiple users to work together on files (GoogleDocs, Office365) and store and share them (Dropbox, OneDrive). However, this can lead to privacy and security conflicts between the users involved, for instance when a user adds someone to a shared folder or changes its permissions. Such multiuser conflicts (MCs), though known to happen in the literature, have not yet been studied in-depth. In this paper, we report a study with 1,050 participants about MCs they experienced in the cloud. We show what are the MCs that arise when multiple users work together in the cloud and how and why they arise, what is the prevalence and severity of MCs, what are their consequences on users, and how do users work around MCs. We derive recommendations for designing mechanisms to help users avoid, mitigate, and resolve MCs in the cloud.