Fix for iBooks "Cannot Open, the Book Is Damaged" Prompt

I read books in iBooks and made quite a few notes. Not long ago, I found the book I was reading had been updated, so I deleted the old version and downloaded the new one. The trouble began: when I opened it, I was told "Cannot be opened. The book is damaged." I got anxious, and following the Windows approach, I kept deleting and re-downloading, but the error kept appearing. Baidu's answers were still the usual vague, useless ones. With no other choice, I reinstalled the system. As for making a Mac bootable USB drive, a few simple disk operations plus one command will do it. Anyway, back to the topic: after reinstalling the system I logged in with my Apple ID, opened iBooks, and — the miracle moment — the prompt was gone. I was secretly pleased, reopened iBooks, and was stunned: the same error. So I thought of customer service, and created a new Apple ID (you can't get through without filling in bank card info — what a hegemonic clause). After logging in to iBooks with the new ID, I got a prompt asking whether to sync notes; I clicked Yes, and the notes came back, the book could be read, and after closing and reopening many times it worked normally. But then I thought: all my other software uses the old ID, and only iBooks uses a new one — wouldn't that be a bit odd? Determined, I switched back, to give it another try, figuring maybe clearing the account info would make the old ID work too. But things were always more serious than we expected. Switching the account back, the problem returned. Switching to the new account, the problem spread. One careless move, eternal regret!

To sum up: on the same computer, just switching the ID allows normal reading; once notes are synced, the problem comes along with the sync — so it must be the notes causing the trouble.

Now, all of the above is filler. The actual solution is as follows. Open iBooks preferences, click the General tab, and uncheck "Sync bookmarks, highlights, and collections across devices". Fully quit iBooks, reopen it, click "Notes" in the top-left, delete all of the notes mentioned below. If you have multiple devices, re-enable "Sync bookmarks, highlights, and collections across devices". After closing and reopening iBooks, deleting and re-downloading books many times, the error has never appeared again.