Unfortunately, Evernote does NOT do the proper internal testing of their updated before releasing them. The last announcement for a production (GA) version is for EN Win 5.8.6 Update.

However, I have not seen, nor can I find, the announcement for EN Win 5.8.8.

Usually Evernote will post a new thread here announcing the update, and you can see responses from users who have tried the update. IME, it is best to wait for at least a week after the release before updating, checking this forum for user reports of problems and/or bugs before you update. I believe that EN Win is telling you that a new version is 'available', not that you 'need' to update. You might also want to submit a bug report (see below). If it is not working, post back here, and we'll try to help. If EN Win 5.8.5 is still working for you, then I'd suggest that you NOT update for a while. After multiple attempts I get a recurring error message when trying to uninstall the previous version that it cant find evernote.msi on the CD/DVD drive. My system tells me that i need to upgrade to 5.8.8.

What is evernote v 5.8.6 on my computer