Firefox uses the Password Manager (logins.json in the Firefox profile folder) to store the credentials to login to Sync, so if Firefox isn't able to log in then it sounds that logins.json is cleared or at least the chrome://FirefoxAccounts entry in this file. This chrome://FirefoxAccounts entry is hidden from about:logins so you won't see it listed there, only a direct inspection of logins.json shows it. You can try to keep a copy of logins.json and check whether it has changed. Other possible causes are a problem with prefs.js of files in the weave folder.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Firefox uses the Password Manager (logins.json in the Firefox profile folder) to store the credentials to login to Sync, so if Firefox isn't able to log in then it sounds that logins.json is cleared or at least the chrome://FirefoxAccounts entry in this file. This chrome://FirefoxAccounts entry is hidden from about:logins so you won't see it listed there, only a direct inspection of logins.json shows it. You can try to keep a copy of logins.json and check whether it has changed. Other possible causes are a problem with prefs.js of files in the weave folder. You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

I have tried deleting all the `chrome://FirefoxAccounts` records and then logging in to sync again but it doesn't work! After restarting windows, Firefox Sync still disconnects!

I have tried logging out of my account and back in. But when booting the OS, still disconnected! Here is the error log I found at about:sync-log

``` 1661220868449 Sync.Status INFO Resetting Status. 1661220868449 Sync.Status DEBUG Status.service: undefined => success.status_ok 1661220868469 FirefoxAccounts TRACE initializing new storage manager 1661220868469 FirefoxAccounts TRACE starting fetch of json user data 1661220868470 Sync.SyncScheduler TRACE Setting SyncScheduler policy values to defaults. 1661220868470 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1661220868470 Sync.Service INFO Loading Weave 1.105.0 1661220868471 Sync.Engine.Clients DEBUG Engine constructed 1661220868472 Sync.Engine.Clients DEBUG Resetting clients last sync time 1661220868484 Sync.Engine.Addons DEBUG Engine constructed 1661220868553 FirefoxAccounts TRACE finished fetch of json user data - took: 83 1661220868553 FirefoxAccounts DEBUG reading secure storage with existing: [] 1661220868553 FirefoxAccounts TRACE starting fetch of user data from the login manager 1661220868559 FirefoxAccounts INFO Can't find any credentials in the login manager 1661220868559 FirefoxAccounts TRACE initializing of new storage manager done 1661220868573 Sync.Engine.Addons DEBUG SyncEngine initialized: addons 1661220868584 Sync.Engine.Bookmarks DEBUG Engine constructed 1661220868599 Sync.Engine.Bookmarks DEBUG SyncEngine initialized: bookmarks 1661220868602 Sync.Engine.Forms DEBUG Engine constructed 1661220868611 FirefoxAccounts DEBUG FxAccountsWebChannel registered: account_updates with origin https://accounts.firefox.com 1661220868640 Sync.Engine.Forms DEBUG SyncEngine initialized: forms 1661220868645 Sync.Engine.History DEBUG Engine constructed 1661220868652 FirefoxAccounts DEBUG FxAccountsProfileClient: Initialized 1661220868653 FirefoxAccounts DEBUG FxAccountsProfileClient: Requested profile 1661220868653 FirefoxAccounts DEBUG getOAuthToken enter 1661220868653 FirefoxAccounts TRACE getCachedToken returning cached token 1661220868653 FirefoxAccounts DEBUG getOAuthToken returning a cached token 1661220868654 Services.Common.RESTRequest DEBUG GET request to https://profile.accounts.firefox.com/v1/profile 1661220868695 FirefoxAccounts INFO fetching updated device list 1661220868763 Services.Common.RESTRequest DEBUG GET request to https://api.accounts.firefox.com/v1/account/devices 1661220868792 Sync.Engine.History DEBUG SyncEngine initialized: history 1661220868796 Sync.Engine.Passwords DEBUG Engine constructed 1661220868920 Sync.Engine.Passwords DEBUG SyncEngine initialized: passwords 1661220868923 Sync.Engine.Prefs DEBUG Engine constructed 1661220868986 Sync.Engine.Prefs DEBUG SyncEngine initialized: prefs 1661220868991 Sync.Engine.Tabs DEBUG Engine constructed 1661220868994 Sync.Engine.Tabs DEBUG SyncEngine initialized: tabs 1661220868994 Sync.Engine.Tabs DEBUG Resetting tabs last sync time 1661220868998 Sync.Engine.CreditCards DEBUG Engine constructed 1661220869006 Sync.Engine.CreditCards DEBUG SyncEngine initialized: creditcards 1661220869012 Sync.Engine.Extension-Storage DEBUG Engine constructed 1661220869081 Sync.Engine.Extension-Storage DEBUG SyncEngine initialized: extension-storage 1661220869082 Sync.Service INFO Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:103.0) Gecko/20100101 Firefox/103.0 1661220869084 Sync.AddonsReconciler INFO Registering as Add-on Manager listener. 1661220869084 Sync.AddonsReconciler DEBUG Adding change listener. 1661220869085 Sync.Engine.History.Tracker INFO Adding Places observer. 1661220869095 FirefoxAccounts INFO Already fetching device list, return existing promise 1661220869097 Sync.Service DEBUG User-Agent: Firefox/103.0.2 (Windows NT 10.0; Win64; x64) FxSync/1.105.0.20220808125904.desktop 1661220869098 Sync.Service INFO Starting sync at 2022-08-23 09:14:29 in browser session QLLPHcuwp5FK 1661220869098 Sync.Service DEBUG In sync: should login. 1661220869098 Sync.Service INFO User logged in successfully - verifying login. 1661220869099 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661220869123 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661220869124 Sync.SyncAuthManager DEBUG unlockAndVerifyAuthState re-fetched credentials and is returning: error.login.reason.account 1661220869124 Sync.Status DEBUG Status.login: success.login => error.login.reason.account 1661220869124 Sync.Status DEBUG Status.service: success.status_ok => error.login.failed 1661220869124 Sync.Service DEBUG Fetching unlocked auth state returned error.login.reason.account 1661220869124 Sync.ErrorHandler ERROR Sync encountered a login error 1661220869125 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1661220869126 Sync.Service DEBUG Exception calling WrappedLock: Error: Login failed: error.login.reason.account(resource://services-sync/service.js:1040:15) JS Stack trace: [email protected]:1040:15 1661220869127 Sync.Service DEBUG Not syncing: login returned false. ```

And this

``` 1661220869128 Sync.LogManager DEBUG Flushing file log 1661220869267 Sync.LogManager DEBUG Log cleanup threshold time: 1660356869267 1661220869282 Sync.LogManager DEBUG Done deleting files. 1661220870656 Services.Common.RESTRequest DEBUG GET https://profile.accounts.firefox.com/v1/profile 304 1661220870728 Services.Common.RESTRequest DEBUG GET https://api.accounts.firefox.com/v1/account/devices 200 1661220870729 Hawk DEBUG (Response) /account/devices: code: 200 - Status text: OK 1661220870729 Hawk DEBUG Clock offset vs https://api.accounts.firefox.com/v1: -1729 1661220870729 FirefoxAccounts INFO Got new device list: 41993f58354b49f4563e0eb72f327554 1661220870730 FirefoxAccounts INFO updating the cache 1661220899226 Sync.RemoteTabs INFO Doing a tab sync. 1661220899226 Sync.Service DEBUG User-Agent: Firefox/103.0.2 (Windows NT 10.0; Win64; x64) FxSync/1.105.0.20220808125904.desktop 1661220899227 Sync.Service INFO Starting sync at 2022-08-23 09:14:59 in browser session QLLPHcuwp5FK 1661220899227 Sync.Service DEBUG In sync: should login. 1661220899227 Sync.Service INFO User logged in successfully - verifying login. 1661220899227 Sync.RemoteTabs INFO Generating tab list with filter 1661220899227 Sync.RemoteTabs INFO Final tab list has 0 clients with 0 tabs. 1661220899241 FirefoxAccounts TRACE not checking freshness of profile as it remains recent 1661220899241 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661220899244 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661220899245 Sync.SyncAuthManager DEBUG unlockAndVerifyAuthState re-fetched credentials and is returning: error.login.reason.account 1661220899245 Sync.Status DEBUG Status.login: error.login.reason.account => error.login.reason.account 1661220899245 Sync.Status DEBUG Status.service: error.login.failed => error.login.failed 1661220899245 Sync.Service DEBUG Fetching unlocked auth state returned error.login.reason.account 1661220899245 Sync.ErrorHandler ERROR Sync encountered a login error 1661220899246 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1661220899247 Sync.Service DEBUG Exception calling WrappedLock: Error: Login failed: error.login.reason.account(resource://services-sync/service.js:1040:15) JS Stack trace: [email protected]:1040:15 1661220899247 Sync.Service DEBUG Not syncing: login returned false. 1661220899248 FirefoxAccounts TRACE not checking freshness of profile as it remains recent ```

Assuming you have connected the same Sync account on both your mobile and desktop copies of Firefox: In Firefox on your desktop device: Go into the Settings menu and select Firefox Account. Tap on Synchronise now

Regards, Will

In case of issues with Sync you can try this:

Disconnect from Sync and Reconnect to Sync again. You can disconnect from Sync by clicking the e-mail address in the "3-bar" Firefox menu button drop-down list or go to "Options/Preferences -> Sync".

Delete the signedInUser.json file in the Firefox profile folder and delete the Weave folder (Sync was formerly named Weave) with Firefox closed.

Remove an existing chrome://FirefoxAccounts entry in the Firefox Password Manager.

If that isn't enough then delete the prefs.js files to reset all prefs and maybe also delete the compatibility.ini file to reinitialize the profile.

Delete and re-create the Firefox account or change the Sync password.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

I logged out firefox from my account, deleted files signedInUser.json, Weave folder, prefs.js and compatibility.ini

Delete all chrome://FirefoxAccounts records in password manager

Delete the Firefox Sync account and create a new account with a new password. But when I restart the OS, everything still disconnects and I still have to manually log in again!

This log

``` 1661311682817 Sync.LogManager DEBUG Flushing file log 1661311682859 Sync.LogManager DEBUG Log cleanup threshold time: 1660447682859 1661311682955 Sync.LogManager DEBUG Done deleting files. 1661311684804 FirefoxAccounts TRACE not checking freshness of profile as it remains recent 1661311684804 FirefoxAccounts TRACE not checking freshness of profile as it remains recent 1661311684829 FirefoxAccounts TRACE not checking freshness of profile as it remains recent 1661311684829 FirefoxAccounts TRACE not checking freshness of profile as it remains recent 1661311689974 Sync.RemoteTabs INFO Generating tab list with filter 1661311689974 Sync.RemoteTabs INFO Final tab list has 0 clients with 0 tabs. 1661311693491 FirefoxAccounts DEBUG FxAccountsWebChannel message received: fxaccounts:fxa_status 1661311693491 FirefoxAccounts DEBUG fxa_status received 1661311693491 FirefoxAccounts DEBUG service: null 1661311693492 FirefoxAccounts DEBUG is private browsing: false 1661311748849 FirefoxAccounts DEBUG FxAccountsWebChannel message received: fxaccounts:fxa_status 1661311748850 FirefoxAccounts DEBUG fxa_status received 1661311748850 FirefoxAccounts DEBUG service: 30b11ae57025e70b 1661311748850 FirefoxAccounts DEBUG is private browsing: false 1661311991426 Sync.RemoteTabs INFO Doing a tab sync. 1661311991426 Sync.Service DEBUG User-Agent: Firefox/104.0 (Windows NT 10.0; Win64; x64) FxSync/1.106.0.20220818191623.desktop 1661311991427 Sync.Service INFO Starting sync at 2022-08-24 10:33:11 in browser session 6Fd_49rMEIu- 1661311991427 Sync.Service DEBUG In sync: should login. 1661311991428 Sync.Service INFO User logged in successfully - verifying login. 1661311991428 Sync.RemoteTabs INFO Generating tab list with filter 1661311991429 Sync.RemoteTabs INFO Final tab list has 0 clients with 0 tabs. 1661311991448 FirefoxAccounts DEBUG FxAccountsProfileClient: Requested profile 1661311991448 FirefoxAccounts DEBUG getOAuthToken enter 1661311991449 FirefoxAccounts TRACE getCachedToken returning cached token 1661311991449 FirefoxAccounts DEBUG getOAuthToken returning a cached token 1661311991449 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661311991455 Services.Common.RESTRequest DEBUG GET request to https://profile.accounts.firefox.com/v1/profile 1661311991455 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661311991456 Sync.SyncAuthManager DEBUG unlockAndVerifyAuthState re-fetched credentials and is returning: error.login.reason.account 1661311991456 Sync.Status DEBUG Status.login: error.login.reason.account => error.login.reason.account 1661311991456 Sync.Status DEBUG Status.service: error.login.failed => error.login.failed 1661311991456 Sync.Service DEBUG Fetching unlocked auth state returned error.login.reason.account 1661311991456 Sync.ErrorHandler ERROR Sync encountered a login error 1661311991457 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1661311991459 Sync.Service DEBUG Exception calling WrappedLock: Error: Login failed: error.login.reason.account(resource://services-sync/service.js:1039:15) JS Stack trace: [email protected]:1039:15 1661311991459 Sync.Service DEBUG Not syncing: login returned false. ```

And this log

``` 1661311991461 Sync.LogManager DEBUG Flushing file log 1661311991482 Sync.LogManager DEBUG Log cleanup threshold time: 1660447991482 1661311991555 Sync.LogManager DEBUG Done deleting files. 1661311992546 Services.Common.RESTRequest DEBUG GET https://profile.accounts.firefox.com/v1/profile 304 1661312004088 Sync.RemoteTabs INFO Doing a tab sync. 1661312004089 Sync.Service DEBUG User-Agent: Firefox/104.0 (Windows NT 10.0; Win64; x64) FxSync/1.106.0.20220818191623.desktop 1661312004089 Sync.Service INFO Starting sync at 2022-08-24 10:33:24 in browser session 6Fd_49rMEIu- 1661312004089 Sync.Service DEBUG In sync: should login. 1661312004089 Sync.Service INFO User logged in successfully - verifying login. 1661312004090 Sync.RemoteTabs INFO Generating tab list with filter 1661312004090 Sync.RemoteTabs INFO Final tab list has 0 clients with 0 tabs. 1661312004105 FirefoxAccounts TRACE not checking freshness of profile as it remains recent 1661312004106 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661312004110 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1661312004110 Sync.SyncAuthManager DEBUG unlockAndVerifyAuthState re-fetched credentials and is returning: error.login.reason.account 1661312004111 Sync.Status DEBUG Status.login: error.login.reason.account => error.login.reason.account 1661312004111 Sync.Status DEBUG Status.service: error.login.failed => error.login.failed 1661312004111 Sync.Service DEBUG Fetching unlocked auth state returned error.login.reason.account 1661312004111 Sync.ErrorHandler ERROR Sync encountered a login error 1661312004112 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1661312004114 Sync.Service DEBUG Exception calling WrappedLock: Error: Login failed: error.login.reason.account(resource://services-sync/service.js:1039:15) JS Stack trace: [email protected]:1039:15 1661312004115 Sync.Service DEBUG Not syncing: login returned false. 1661312004116 FirefoxAccounts TRACE not checking freshness of profile as it remains recent ```

I tried creating an account for the 3rd time, completely out of sync old data. But when starting the operating system, Firefox Sync is still disconnected now.

Here log

``` 1662000172620 FirefoxAccounts TRACE initializing new storage manager 1662000172621 FirefoxAccounts TRACE starting fetch of json user data 1662000172673 FirefoxAccounts TRACE finished fetch of json user data - took: 52 1662000172674 FirefoxAccounts DEBUG reading secure storage with existing: [] 1662000172674 FirefoxAccounts TRACE starting fetch of user data from the login manager 1662000172678 FirefoxAccounts INFO Can't find any credentials in the login manager 1662000172678 FirefoxAccounts TRACE initializing of new storage manager done 1662000172707 Services.Common.RESTRequest DEBUG GET request to https://api.accounts.firefox.com/v1/account/attached_clients 1662000172786 Sync.Status INFO Resetting Status. 1662000172786 Sync.Status DEBUG Status.service: undefined => success.status_ok 1662000172792 Sync.SyncScheduler TRACE Setting SyncScheduler policy values to defaults. 1662000172792 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1662000172793 Sync.Service INFO Loading Weave 1.106.0 1662000172794 Sync.Engine.Clients DEBUG Engine constructed 1662000172795 Sync.Engine.Clients DEBUG Resetting clients last sync time 1662000172808 Sync.Engine.Addons DEBUG Engine constructed 1662000172837 Sync.Engine.Addons DEBUG SyncEngine initialized: addons 1662000172847 Sync.Engine.Bookmarks DEBUG Engine constructed 1662000172862 Sync.Engine.Bookmarks DEBUG SyncEngine initialized: bookmarks 1662000172865 Sync.Engine.Forms DEBUG Engine constructed 1662000172896 FirefoxAccounts DEBUG FxAccountsWebChannel registered: account_updates with origin https://accounts.firefox.com 1662000172907 FirefoxAccounts DEBUG FxAccountsProfileClient: Initialized 1662000172907 FirefoxAccounts DEBUG FxAccountsProfileClient: Requested profile 1662000172908 FirefoxAccounts DEBUG getOAuthToken enter 1662000172908 FirefoxAccounts TRACE getCachedToken returning cached token 1662000172908 FirefoxAccounts DEBUG getOAuthToken returning a cached token 1662000172908 Services.Common.RESTRequest DEBUG GET request to https://profile.accounts.firefox.com/v1/profile 1662000172950 FirefoxAccounts INFO fetching updated device list 1662000172956 Services.Common.RESTRequest DEBUG GET request to https://api.accounts.firefox.com/v1/account/devices 1662000172977 Sync.Engine.Forms DEBUG SyncEngine initialized: forms 1662000172981 Sync.Engine.History DEBUG Engine constructed 1662000173004 Sync.Engine.History DEBUG SyncEngine initialized: history 1662000173008 Sync.Engine.Passwords DEBUG Engine constructed 1662000173064 Sync.Engine.Passwords DEBUG SyncEngine initialized: passwords 1662000173068 Sync.Engine.Prefs DEBUG Engine constructed 1662000173161 Sync.Engine.Prefs DEBUG SyncEngine initialized: prefs 1662000173167 Sync.Engine.Tabs DEBUG Engine constructed 1662000173181 Sync.Engine.Tabs DEBUG SyncEngine initialized: tabs 1662000173181 Sync.Engine.Tabs DEBUG Resetting tabs last sync time 1662000173185 Sync.Engine.CreditCards DEBUG Engine constructed 1662000173187 Sync.Engine.CreditCards DEBUG SyncEngine initialized: creditcards 1662000173193 Sync.Engine.Extension-Storage DEBUG Engine constructed 1662000173204 Sync.Engine.Extension-Storage DEBUG SyncEngine initialized: extension-storage 1662000173205 Sync.Service INFO Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0 1662000173207 Sync.AddonsReconciler INFO Registering as Add-on Manager listener. 1662000173207 Sync.AddonsReconciler DEBUG Adding change listener. 1662000173209 Sync.Engine.History.Tracker INFO Adding Places observer. 1662000173222 FirefoxAccounts INFO Already fetching device list, return existing promise 1662000173222 Sync.Service DEBUG User-Agent: Firefox/104.0.1 (Windows NT 10.0; Win64; x64) FxSync/1.106.0.20220829141339.desktop 1662000173223 Sync.Service INFO Starting sync at 2022-09-01 09:42:53 in browser session 05o9k8f6ILMg 1662000173223 Sync.Service DEBUG In sync: should login. 1662000173223 Sync.Service INFO User logged in successfully - verifying login. 1662000173224 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1662000173247 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1662000173247 Sync.SyncAuthManager DEBUG unlockAndVerifyAuthState re-fetched credentials and is returning: error.login.reason.account 1662000173247 Sync.Status DEBUG Status.login: success.login => error.login.reason.account 1662000173247 Sync.Status DEBUG Status.service: success.status_ok => error.login.failed 1662000173247 Sync.Service DEBUG Fetching unlocked auth state returned error.login.reason.account 1662000173248 Sync.ErrorHandler ERROR Sync encountered a login error 1662000173248 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1662000173249 Sync.Service DEBUG Exception calling WrappedLock: Error: Login failed: error.login.reason.account(resource://services-sync/service.js:1039:15) JS Stack trace: [email protected]:1039:15 1662000173250 Sync.Service DEBUG Not syncing: login returned false. ```

And

``` 1662000173251 Sync.LogManager DEBUG Flushing file log 1662000173387 Sync.LogManager DEBUG Log cleanup threshold time: 1661136173387 1662000173405 Sync.LogManager DEBUG Done deleting files. 1662000175564 Sync.RemoteTabs INFO Doing a tab sync. 1662000175564 Sync.Service DEBUG User-Agent: Firefox/104.0.1 (Windows NT 10.0; Win64; x64) FxSync/1.106.0.20220829141339.desktop 1662000175564 Sync.Service INFO Starting sync at 2022-09-01 09:42:55 in browser session 05o9k8f6ILMg 1662000175564 Sync.Service DEBUG In sync: should login. 1662000175564 Sync.Service INFO User logged in successfully - verifying login. 1662000175565 Sync.RemoteTabs INFO Generating tab list with filter 1662000175565 Sync.RemoteTabs INFO Final tab list has 0 clients with 0 tabs. 1662000175593 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1662000175596 FirefoxAccounts INFO Can't get keys; no key material or tokens available 1662000175596 Sync.SyncAuthManager DEBUG unlockAndVerifyAuthState re-fetched credentials and is returning: error.login.reason.account 1662000175596 Sync.Status DEBUG Status.login: error.login.reason.account => error.login.reason.account 1662000175596 Sync.Status DEBUG Status.service: error.login.failed => error.login.failed 1662000175596 Sync.Service DEBUG Fetching unlocked auth state returned error.login.reason.account 1662000175596 Sync.ErrorHandler ERROR Sync encountered a login error 1662000175596 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1662000175597 Sync.Service DEBUG Exception calling WrappedLock: Error: Login failed: error.login.reason.account(resource://services-sync/service.js:1039:15) JS Stack trace: [email protected]:1039:15 1662000175597 Sync.Service DEBUG Not syncing: login returned false. ```