# Differences between Mathematica versions 11 and 12 regarding ODE solution

Solving the ODE

$$(\lambda +y(x)) y”(x)-y'(x)^2-1=0$$

with Version 11 I got the solution

yx = 1/2 (Exp[-Exp[C[1]] (C[2] + x) - 2 C[1]] + Exp[Exp[C[1]] (C[2] + x)] - 2 lambda) 

while in Version 12 for the same ODE I got the solution

yx = -lambda - Tanh[E^C[1] (x + C[2])]^2/Sqrt[-E^(2 C[1]) Sech[E^C[1] (x + C[2])]^2 Tanh[E^C[1] (x + C[2])]^2] 

This last result isn’t ever real: see the denominator. My question is regarding how to ask the solver in Version 12 to obtain the Version 11 answer. Thanks.