iOS 8.4.1 Issues: iBooks keeps crashing

iOS and iPadOS

Hello, everyone. I have some problems with iBooks app on my iPhone 6. I downloaded iOS 8.4.1 on my phone, and I found that I can't even open iBooks, and it shows a gray screen and then returns to home. It seems like freezing and crashing. Have anyone met the same problem? Please help, thanks in advance.