Make sure toolbars like the "Bookmarks Toolbar" are visible. Open the Customize page and set what toolbars (Show/Hide Toolbars) and toolbar items to display.

• Right-click empty toolbar area -> Customize
• "3-bar" menu button -> Customize
• View -> Toolbars
  *you can tap the Alt key or press the F10 key to show the hidden Menu Bar temporarily

• check that "Bookmarks Toolbar Items" is on the Bookmarks Toolbar
• if "Bookmarks Toolbar Items" is not on the Bookmarks Toolbar then drag it back from the Customize palette to the Customize page to the Bookmarks Toolbar

• if missing items are in the Customize palette then drag them back from the Customize page to the toolbar
• if you do not see an item on a toolbar and in the Customize palette then click Restore Defaults in the Customize palette window to restore the default toolbar set.

• https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars

cor-el, I'm afraid I wasn't clear. I have no problem customizing the taskbar; my problem is that I can't seem to add links to the bookmarks bar. I used to be able to drag the padlock to the bar, and the link would appear in the bar or the overflow; now, the link doesn't move to the bar or the overflow. What am I missing?

Your problem might be that the "Bookmarks Toolbar Items" control isn't positioned on the Bookmarks Toolbar. You can check that in customize mode.

• https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars

Do you see any bookmarks on the Bookmarks Toolbar assuming that you have bookmarks in the Bookmarks Toolbar folder ?

You can open the sidebar (Ctrl+B) and drag the tab to Bookmarks Toolbar folder in the sidebar to see if that allows to add the bookmark. If that works, but you do not see the bookmark on the Bookmarks Toolbar then you will have to check for issues with the places.sqlite database.

If you use Sync then best is to disconnect Sync temporarily during troubleshooting.

This could be a problem with the places.sqlite and favicons.sqlite files in the Firefox profile folder.

• use the "Places Database" -> "Verify Integrity" button on the "Help -> More Troubleshooting Information" (about:support) page

If errors are reported with "Verify Integrity", close and restart Firefox or reboot and retry.

If "Verify Integrity" cannot repair places.sqlite, rename/remove all places.sqlite and favicons.sqlite files in the Firefox profile folder with Firefox closed. Firefox will rebuild places.sqlite and restore the bookmarks from the most recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• you lose the history when a new places.sqlite is created

You may have to restore an older bookmarks backup in the bookmarkbackups folder via the Bookmarks Manager (Library).

• Bookmarks -> Show All Bookmarks -> Import & Backup -> Restore
• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them

See also:

• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional
• https://support.mozilla.org/en-US/kb/cant-add-change-or-save-bookmarks

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

cor-el, I had to verify things two or three times, but now all is well.

Thanks for your help.