Can you remove the bookmark elsewhere like in the Bookmarks Manager (Library) or in the sidebar ?

• https://support.mozilla.org/en-US/kb/how-do-i-delete-bookmark

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

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

You can check for issues with the places.sqlite and favicons.sqlite databases 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/Bookmarks+not+saved#w_fix-the-bookmarks-file
• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

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.

• 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

Thanks for your answer but it didn't work.

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Hi, Disabling hardware acceleration has also not settled the case.

Regarding the theme, I do not see any particular theme "by default". (see photo)

The only way to remove these vertical favorites is to go through the Favorites Manager.

The screenshot shows the recommendations. Installed themes would be under Themes and also under "Customize -> Themes".

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

There is not default themes shown...

I can't do anything with every vertical bookmarks (modfiy, delete, etc.). I can just launch it. That's all.

Did you try the Verify integrity button, as suggested previously? It should output a log. Paste this log here for an analysis.

Verify integrity didn't do the trick...

Task: checkIntegrity + The places.sqlite database is sane + The favicons.sqlite database is sane > Task: invalidateCaches + The caches have been invalidated > Task: checkCoherence + The database is coherent > Task: expire + Database cleaned up > Task: originFrecencyStats + Recalculated origin frecency stats > Task: vacuum + Initial database size is 5120KiB + The database has been vacuumed + Final database size is 5120KiB > Task: stats + Places.sqlite size is 5120KiB + Favicons.sqlite size is 2304KiB + pragma_user_version is 57 + pragma_page_size is 32768 + pragma_cache_size is -2048 + pragma_journal_mode is wal + pragma_synchronous is 1 + History can store a maximum of 39244 unique pages + Table moz_places has 834 records + Table moz_historyvisits has 147 records + Table moz_inputhistory has 0 records + Table moz_hosts has 0 records + Table moz_bookmarks has 806 records + Table moz_bookmarks_deleted has 0 records + Table moz_keywords has 1 records + Table sqlite_sequence has 1 records + Table moz_anno_attributes has 2 records + Table moz_annos has 2 records + Table moz_items_annos has 0 records + Table sqlite_stat1 has 20 records + Table moz_meta has 7 records + Table moz_origins has 506 records + Table moz_places_metadata has 0 records + Table moz_places_metadata_search_queries has 0 records + Index sqlite_autoindex_moz_inputhistory_1 + Index sqlite_autoindex_moz_hosts_1 + Index sqlite_autoindex_moz_bookmarks_deleted_1 + Index sqlite_autoindex_moz_keywords_1 + Index sqlite_autoindex_moz_anno_attributes_1 + Index sqlite_autoindex_moz_origins_1 + Index sqlite_autoindex_moz_places_metadata_search_queries_1 + Index moz_places_url_hashindex + Index moz_places_hostindex + Index moz_places_visitcount + Index moz_places_frecencyindex + Index moz_places_lastvisitdateindex + Index moz_places_guid_uniqueindex + Index moz_historyvisits_placedateindex + Index moz_historyvisits_fromindex + Index moz_historyvisits_dateindex + Index moz_bookmarks_itemindex + Index moz_bookmarks_parentindex + Index moz_bookmarks_itemlastmodifiedindex + Index moz_bookmarks_dateaddedindex + Index moz_bookmarks_guid_uniqueindex + Index moz_keywords_placepostdata_uniqueindex + Index moz_annos_placeattributeindex + Index moz_items_annos_itemattributeindex + Index moz_places_originidindex + Index moz_places_metadata_placecreated_uniqueindex > Task: _refreshUI

I even reinstall firefox : same thing. All vertical bookmark from personnal bookmark line are concerned.

Can't you remove the bookmark in the sidebar or the Library as well ?

Yes, As already said, I can manage bookmarks in bookmarks manager (modify or delete).

But impossible to do directly those types of actions from the 13th line on the dropdown bookmarks menus.

Note that vertical emplacement of the bookmark is in question !

May be a problem of style, interline, line height...