
In some cases, Zotero may not copy the correct directory and instead either create a new data directory or migrate the data directory from the wrong profile, potentially leaving you with an empty or outdated database. (See Zotero Data for the default location on your platform.) If you previously used both Zotero for Firefox and Zotero Standalone and chose not to share a data directory, you may have a Zotero database in both profile directories, and Zotero will automatically use whichever database was modified more recently. When you first start Zotero 5.0, it attempts to migrate your data directory to a new default location, a “Zotero” directory in your home directory. Zotero 4.0 and earlier stored data by default in a 'zotero' directory within either the Zotero profile directory or the Firefox profile directory.
