All settings, history, tabs, add-ons, etc. are default as if a new install. The upgrade history of Firefox remains. Latest: 3 of 4 files in default profile folder ysb3r7f8.default > sessionstore-backups > previous.jsonlz4, recovery.baklz4 & upgrade.jsonlz4-20180315233128 (written in Chinese text with some scattered blue & red characters). A similarly named and sized file, recovery.jsonlz4, is in English. (viewed contents with Notepad) How to restore Firefox with 1of 2 found older backup folders and their contained files? Profile & Backup files Large 35 KB Chinese crashes/store.json.mozlz4 file: 潭䱺㑺0繟ヿ≻≶ㄺ∬牣獡敨≳笺ㄢ摡㡤攴ⴵ㌹慦㐭㡦ⵡ㤹㌷㌭昰㤹摤慣㔵... d6elgczp.default-1511941882523/sessionstore-backups/ previous.jsonlz4 03/19/2018 11:34 PM recovery.baklz4 03/20/2018 7:36 PM recovery.jsonlz4 03/20/2018 7:36 PM upgrade.jsonlz4-20180206200532 2/7/2018 9:31 PM upgrade.jsonlz4-20180310025718 3/13/2018 9:50 PM upgrade.jsonlz4-20180315233128 3/16/2018 3:38 PM Small 1 KB English crashes/store.json.mozlz4 file: mozLz40 8 ô{"v":1,"crashes":{},"countsByDay ð
rruptDate":null} 6j0bu831.default/sessionstore-backups/ previous.js 10/5/2017 8:07 PM previous.jsonlz4 11/27/2017 7:40 PM recovery.baklz4 11/28/2017 3:47 PM recovery.jsonlz4 11/28/2017 3:47 PM upgrade.js-20150122214805 10/5/2017 8:07 PM upgrade.jsonlz4-20170926190823 10/5/2017 9:50 PM upgrade.jsonlz4-20171024165158 10/26/2017 1:15 PM upgrade.jsonlz4-20171112125346 11/17/2017 8:58 PM