I tried to update Zotero but I keep receiving this message: the update could not be installed. Please make sure there are no other copies of Zotero running on your computer, and then restart Zotero to try again.
Just re-install Zotero instead, then (that does the same as an update). Do make sure to have a back-up of your data folder, but in all expectations, Zotero will just start up with all your data after re-install.
the update could not be installed. Please make sure there are no other copies of Zotero running on your computer, and then restart Zotero to try again.