Fatal error: Call to undefined function wp_get_current_user() after update

Hi! I am getting

Fatal error: Call to undefined function wp_get_current_user() in Fatal error: Call to undefined function wp_get_current_user()

after updating this plugin. I tried several times, checking the file permission (755) in the file manager but still getting that fatal error. Thus, I have reverted back to version 4.0.9.