I deleted it and gnus works now. Thank you, guys!

BR,
Vincent Zhang
在 2019年12月28日 +1300 13:52，Lars Ingebrigtsen <larsi@gnus.org>，写道：
> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
> > Vincent Zhang <seagle0128@gmail.com> writes:
> >
> > > Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
> > > <=(nil 6)
> > > gnus-get-unread-articles(nil nil)
> > > gnus-setup-news(nil nil nil)
> > > #f(compiled-function () #<bytecode 0x1ff08dde5bdd>)()
> > > gnus-1(nil nil nil)
> > > gnus(nil)
> >
> > This happens when the variable `gnus-group-list-mode' is nil, which it
> > shouldn't be. Nothing has touched that variable any time recently -- can
> > you do some poking around and figure out why it's nil?
>
> No, this was due to the recent gnus-start.el changes, and it should now
> be fixed on both Emacs 27 and the trunk.
>
> There may be extra nil entries in the start of gnus-newsrc-alist in
> .newsrc.eld -- if there are, delete them.
>
> --
> (domestic pets only, the antidote for overdose, milk.)
> bloggy blog: http://lars.ingebrigtsen.no