View source for Preferences not saved

This article deals with changes to options or preference settings not being saved after you restart your Mozilla application.   If [[Toolbar customization - Firefox|Firefox toolbar customizations]] are not being saved, see [[Corrupt localstore.rdf |this article]]. 

==Read-only or locked preference file==
The inability to save any preference changes can be caused by having a read-only or locked [[prefs.js file]] or "prefs.js.moztmp" file in the [[profile folder]].   You may receive an error similar to "Failed to save the preferences file.  Any preference changes will be lost at the end of the session"  [http://forums.mozillazine.org/viewtopic.php?t=455989].  You may also find multiple files named "prefs-<n>.js" (where <n> is a number) in the profile folder.  Check the file properties of the prefs.js file (and  "prefs.js.moztmp" file, if found) and make sure that the "read-only" attribute is not set.   See [[Multiple profile files created]] for additional information.

==Corrupt or damaged prefs.js file==
If the [[prefs.js file]] is corrupt or damaged to the exent that it is no longer writable, it can prevent preference changes from being saved.  [http://forums.mozillazine.org/viewtopic.php?f=38&t=892825] [http://forums.mozillazine.org/viewtopic.php?t=661250]   In such cases you will need to replace the corrupt or damaged file.  [[Kill application|Close your Mozilla application]] (if open) and,
* If you have a current [[profile backup]],  replace the prefs.js file in your [[profile folder]] with the backup copy. 
* If you have no backup,  open the profile folder and rename prefs.js to prefs.jsOLD.  A new prefs.js file will be generated when you next open your Mozilla application.  (You can alternately use the [[Safe Mode|Firefox Safe Mode]] option, "Reset all user preferences to Firefox defaults" to rebuild the prefs.js file from program defaults, the same as if you manually deleted the file.)  All preferences will be reset to default values but future changes will be saved.

'''Note:''' The above fix may also resolve an issue in which an additional "Firefox Updated" tab opens a page stating, ''You’ve been updated to the latest version of Firefox'',  each time you restart Firefox.  [https://bugzilla.mozilla.org/show_bug.cgi?id=485830]

===Recovering lost settings===
If preference settings have been lost due to a corrupt or damaged prefs.js file, you may be able to recover the missing settings, including Mozilla Suite/SeaMonkey or Thunderbird mail account settings,  if the [[profile folder]] contains a "prefs-1.js" file that includes the missing settings.  If this file exists,  [[Kill application|exit your Mozilla application]] (if open), remove (or rename) your existing prefs.js file and then rename "prefs-1.js" to "prefs.js".   [http://forums.mozillazine.org/viewtopic.php?f=28&t=898265].  For additional information on recovering lost mail account settings, see [[Recovering a profile that suddenly disappeared#Corrupt or empty prefs.js|Recovering a profile that suddenly disappeared - Corrupt or empty prefs.js]].

==Other software prevents preference changes==
* Dell Network Assistant can lock or "protect" the preferences file.  If you have this program,  try disabling or uninstalling it.  [http://forums.mozillazine.org/viewtopic.php?t=461093]  
*McAfee Privacy Service can disable your Mozilla browser's popup blocker.  If you use McAfee, you will need to select the option to block popup ads within the McAfee Security Center settings. See [[Popups_not_blocked#Other_software_disables_the_popup_blocker|this article]] for details.
* Norton 360 includes a "Firefox Privacy Cleanup" feature that, if enabled,  overrides your Firefox Privacy settings and prevents you from keeping your Browsing History, [[Cookies]]  or other private data between sessions.   If you use Norton 360,  deselect the "Firefox Privacy Cleanup" option in your Norton 360 settings. [https://support.mozilla.org/kb/Configuring+Norton+360#_Firefox_Privacy_Cleanup]  
* Various other computer "cleanup" programs can override your Mozilla browser's Privacy settings and remove private data.  [http://forums.mozillazine.org/viewtopic.php?p=1415340#p1415340]

==User.js file locks certain preferences==
If you are able to change some preference settings but not others,  look for a [[user.js file]] in your [[profile folder]] (Windows users, read [[Finding the profile folder on Windows |this]] for help finding it).  The user.js file does not exist by default; it is created by users and, in a few  cases, by [[Resetting_preferences#Software_that_changes_preference_settings |some software programs]], so that certain settings get written back to the [[prefs.js file]] each time you restart your Mozilla application  If you find a user.js file, either remove it from the profile folder or edit the file to remove any unwanted settings.  See  [[Resetting preferences]]  for more information.

==Other solutions==
*Some preferences might be synced, so if you use Sync in Firefox and sync the Preferences then check if there is a corresponding services.sync.prefs.sync.* pref that is set to true that could cause prefs to get changed by other connected devices [https://developer.mozilla.org/Archive/Mozilla/Firefox_Sync/Syncing_custom_preferences].<br />See [[about:config]] for more information about preferences.<br />You can disconnect Sync temporarily to prevent syncing preferences to check if that helps.
*Your Mozilla application may have been customized  to use a "mozilla.cfg" file in the [[installation directory]] to initialize or lock certain preferences.  Note that the content of this file can be obfuscated  (see [[Locking preferences]]). This also involves another file that specifies to use the mozilla.cfg file (probably in the ''\defaults\pref'' folder), so it's best to remove the installation directory and reinstall your Mozilla application (e.g., perform a [[Standard diagnostic - Firefox#Clean reinstall| clean reinstall]] of Firefox by first removing the "Mozilla Firefox" program folder).  If you don't know how the customized settings were added, you may also wish to [[Standard_diagnostic_-_Firefox#Check_for_malware| check for malware]]. [https://support.mozilla.org/questions/938518] [https://support.mozilla.org/questions/944575]
*[[Problematic extensions]] can change certain preferences settings, causing your changes not to be saved [http://forums.mozillazine.org/viewtopic.php?t=642871].   To see if an extension is causing the problem, disable it  (or [[Uninstalling add-ons|uninstall unneeded extensions]]) and then make your preference changes.  (Note that preference changes made by some extensions will persist even after the extension is uninstalled or disabled, until you change the settings.) 
*The [[Standard diagnostic]] provides a basic troubleshooting guide if the preceding suggestions do not fix the problem.

==See also==
*[[Locking preferences]]

==External links==
* [https://developer.mozilla.org/en-US/docs/XUL/School_tutorial/Handling_Preferences Handling Preferences] at developer.mozilla.org
* [http://support.mozilla.org/kb/Preferences+are+not+saved Preferences are not saved (Firefox Support)]
* [http://support.mozilla.org/kb/Private+Browsing Private Browsing] 
* [https://bugzilla.mozilla.org/show_bug.cgi?id=710056 Thunderbird bug report about column settings not being remembered]

[[Category:Configuration]]
[[Category:Issues (Firefox)]]
[[Category:Issues (Mozilla Suite)]]
[[Category:Issues (Thunderbird)]]