Question: dsolve invalid input when plotting

ode := diff(x(t), t, t) = 1^2*(cosh(x(t))-1)/cosh(x(t))

ics := x(0) = 2, (D(x))(0) = 0

xs := dsolve({ics, ode})

 

plot(xs, t = 0 .. 3)

 

why do i get this error?

Error, invalid input: plot expects its 1st argument, p, to be of type {set, array, list, rtable, algebraic, procedure, And(`module`, appliable)}, but received x(t) = RootOf(Int(1/(-4*arctan(exp(_a))+4*arctan(exp(2))-4+2*_a)^(1/2), _a = _Z .. 2)+t)

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