Evernote has sent an email to users warning of a serious bug "in some versions of Evernote for Mac that can cause images and other attachments to be deleted from a note under specific conditions." The company claims only "a small number of people" are affected, but those who have received the email will need to update their Mac app as soon as possible. The glitch occurs in the September version of the software, and less frequently in the versions released since June. TechCrunch reports: In these applications, certain sequences of events can cause an image or other attachments to be deleted from notes without warning, but text is not affected. For example, the bug can be triggered by skimming quickly through a large number of notes, Evernote says. The email explains that once the company identified the problem, it worked quickly to implement a solution and attempted to restore all lost data. The issue was under discussion in Evernote's forums earlier this month. For heavy Evernote users, the bug could have a major impact. One user in the forums posted that they had 20,000 notes in their Evernote account, as part of their PhD research. Hundreds (or maybe even thousands) of their notes may have now become corrupted, according to their post. Unfortunately for some affected users, data recovery was not possible through automated means, the company's email stated. Instead, Evernote is advising those users who are missing attachments to use Evernote's note history feature in Evernote Premium to try to recover the missing data.