The primary cause of QuickBooks Error 15215 is an incorrect setting of Microsoft Internet Explorer (IE). QuickBooks usually double-checks the digital certificates on all files. These steps are taken for all downloaded apps to protect your computer and its contents. The verification may be unfinished or an issue may arise throughout this procedure. This might result in the verification remaining incomplete. It's also possible that no authentication will be carried out at all. The error message is shown as a result of inaccurate or no verification.