An open connection blocks a separate connection's setVersion call On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS IndexedDB == null is false IndexedDB.open('set-version-blocked') IndexedDB.open('set-version-blocked') connections[0].setVersion('version 1') seen_blocked_event = true PASS blocked_event.version is "version 1" PASS blocked_event.target.readyState is 1 connections[1].close() in setVersion.onsuccess PASS seen_blocked_event is true Deleted all object stores. PASS successfullyParsed is true TEST COMPLETE