Locked or damaged places.sqlite
This article applies to Firefox 3.0 and above.
Starting in Firefox 3, bookmarks and browsing history are stored in the places.sqlite file, located in the Firefox profile folder. If the Places database is locked or damaged, many Firefox functions will not work and the following symptoms may occur:
- Firefox opens to a blank page instead of the home page
- Toolbar buttons such as Back/Forward are disabled
- Bookmarks and history are missing
- URL is not updated in the Location Bar as you browse
- Bookmarking a page has no effect
- Unable to delete, move, or edit certain bookmarks
Note: For other solutions to missing bookmarks, see Lost bookmarks. If changes made to bookmarks are lost when you restart Firefox, see Bookmarks not saved. If deleting a large quantity of bookmarks is very slow or causes a hang, see Firefox hangs.
Locked Places database
If Firefox works normally when you first open it after starting up the computer but multiple symptoms arise after you close and later reopen Firefox, it's likely that a Firefox process from a previous session did not close properly and the Places database ("places.sqlite" file) is locked. To work around the issue, close Firefox completely, end any Firefox processes (or reboot the computer), and restart Firefox. 
If this is a recurring problem, see Firefox hangs - Hang at exit and check for problematic extensions. If you use Norton 360 2.0 or Norton Internet Security 2008.5, this is a known issue.  To resolve, update to Norton Internet Security 2009 (or above). If you use Norton 360, run Norton LiveUpdate and install all updates (for more help, contact Norton Support). If the problem persists, either disable "Phishing Protection" in Norton's settings  or delete "coFFPlgn.dll" from the Firefox components folder (details here) to remove the Norton anti-phishing toolbar from Firefox. 
Note: Starting in Firefox 3.5, if you open Firefox and the Places database is locked you will see the message, The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem. 
Damaged Places database
If the symptoms described above occur even when you first start Firefox after rebooting the computer, the Places database (places.sqlite file) may be damaged or missing essential information. If you have a recent profile backup you can remove the file "places.sqlite" (and "places.sqlite-journal", if found) from the Firefox profile folder and replace it with the "places.sqlite" backup. If you have no backup or if it doesn't resolve the problem, you can rebuild the Places database as follows: (You may wish to export your bookmarks to an HTML file first, as a precaution.)
- Close Firefox completely
- Open the Firefox profile folder
- Delete or rename all files named "places.sqlite", including "places.sqlite-journal" and any "places.sqlite.corrupt" files, if found.
When you restart Firefox, "places.sqlite" will be rebuilt and your bookmarks will be automatically restored from the latest JSON bookmark backup; however, your browsing history will be lost.    
Note: In rare cases, your JSON bookmark backup files may also be damaged. You can optionally rebuild the Places database without using any JSON backups by also removing all "bookmarks-(date).json" files from the bookmarkbackups folder but this will result in missing bookmarks unless the profile folder contains a bookmarks.html file with your current bookmarks. If you have a bookmarks.html export or a saved copy of bookmarks.html, you can place it in the Firefox profile folder after removing the "places.sqlite*" and all JSON bookmark backups and Firefox will use those bookmarks to rebuild "places.sqlite".
If your Firefox profile folder includes a "places.sqlite.corrupt" file in addition to "places.sqlite", one reported fix is to open the Firefox profile folder and, after closing Firefox completely, delete or rename the places.sqlite file and then rename "places.sqlite.corrupt" to "places.sqlite". (If you see any other places.sqlite* files, delete those as well, so that only one places.sqlite file remains.) It is possible that certain security or "cleanup" software (e.g., CCleaner) is causing the places.sqlite file corruption. It is also possible that Firefox was not closed properly, as might happen when your computer loses power with Firefox running, which can cause a corrupt places.sqlite file. Always make sure that you close Firefox properly (e.g., no Firefox processes in the Windows Task Manager) before shutting down the computer. 
Problems limited to bookmarks
If the Places database damage seems to be limited to bookmarks, for example, if certain bookmarks cannot be deleted, moved, or edited , try creating a new bookmark backup file in Firefox ("Bookmarks -> Organize Bookmarks -> Import and Backup -> Backup") and then restore the new backup, as an alternative to rebuilding the Places database. This may work since, in Firefox 3.0.5 and above, the bookmark backup process bypasses certain invalid places.sqlite entries that may exist.  and has the advantage of preserving your browsing history. Using PC Tools Spyware Doctor is reported to cause this type of bookmark damage so you should contact PC Tools support for a solution or else stop using the software.   
- A Windows user reports that running the CHKDSK utility fixed the Places database corruption that occurred after a crash. 
- A Linux user suggests that you check file permissions within your profile directory (e.g. ~/.mozilla/firefox/ljzv2exp.default/). 
- Linux users report that updating Sqlite and then removing all places.sqlite* files resolves the issue. For more information, read this Firefox Support topic and this forum thread.
- A Mac user reports multiple problems with bookmarks and history if the environment variable
DYLD_LIBRARY_PATHis set for the login via the file ~/.MacOSX/environment.plist. Removing "environment.plist" and then logging out and back in resolves the issue. 
- Go through the standard diagnostic steps or create a new Firefox profile to see if that solves the problem. 
- Firefox 3.5 implements preventative maintenance for places.sqlite   so, you are still using Firefox 3.0, upgrade Firefox to the latest version, available here.
- Bookmarks and toolbar buttons not working after upgrading (Firefox Support)
- QA/Firefox3/Investigation/Norton 360 (mozilla wiki)
- Issue: Norton-like symptoms but not Norton 360 (Firefox Support Contributors forum topic)
- Places (MDC)
Related bug reports
- Bug 414715 - Notify the user if places.sqlite is locked and bookmarks and history will not work
- Bug 421482 - Firefox 3 uses fsync excessively
- Bug 431558 - implement preventive maintenance for places.sqlite
- Bug 449187 - Seem to have firefox locking up on exit, maintaining a file lock on all the profile files. Bookmarks & history gone, navigation buttons disabled when next opened.
- Bug 452193 - Places Library window is empty due to corrupt places.sqlite (invalid left pane root)
- Bug 452469 - Symantec Norton 360 - Firefox locks sqlite files (Bookmarks are not visible, Users are not able to add bookmarks etc)
- Bug 456910 - Stop using exclusive locking in places
- Bug 462760 - Bookmarks and history do not work.
- Bug 464486 - lots of bookmark corruption reported via user support
- Bug 465684 - Some Bookmarks and some folders have become corrupt and cannot be deleted