diff --git a/lib/OrdinaryDiffEqCore/src/initialize_dae.jl b/lib/OrdinaryDiffEqCore/src/initialize_dae.jl
index 0034e55d9a..67107ac335 100644
--- a/lib/OrdinaryDiffEqCore/src/initialize_dae.jl
+++ b/lib/OrdinaryDiffEqCore/src/initialize_dae.jl
@@ -44,36 +44,14 @@ end
 
 ## Default algorithms
 
-function _initialize_dae!(integrator, prob::ODEProblem,
-        alg::DefaultInit, x::Val{true})
-    if SciMLBase.has_initializeprob(prob.f)
-        _initialize_dae!(integrator, prob,
-            OverrideInit(integrator.opts.abstol), x)
-    else
-        _initialize_dae!(integrator, prob,
-            BrownFullBasicInit(integrator.opts.abstol), x)
-    end
-end
 
 function _initialize_dae!(integrator, prob::ODEProblem,
-        alg::DefaultInit, x::Val{false})
-    if SciMLBase.has_initializeprob(prob.f)
-        _initialize_dae!(integrator, prob,
-            OverrideInit(integrator.opts.abstol), x)
-    else
-        _initialize_dae!(integrator, prob,
-            BrownFullBasicInit(integrator.opts.abstol), x)
-    end
-end
-
-function _initialize_dae!(integrator, prob::DAEProblem,
-        alg::DefaultInit, x::Val{false})
+        alg::DefaultInit, x::Union{Val{true}, Val{false}})
     if SciMLBase.has_initializeprob(prob.f)
         _initialize_dae!(integrator, prob,
             OverrideInit(integrator.opts.abstol), x)
-    elseif prob.differential_vars === nothing
-        _initialize_dae!(integrator, prob,
-            ShampineCollocationInit(), x)
+    elseif !isdefined(Main, :OrdinaryDiffEqNonlinearSolve)
+        throw("`OrdinaryDiffEqNonlinearSolve` is not loaded, which is required for the default initialization algorithm (`BrownFullBasicInit` or `ShampineCollocationInit`). To solve this problem, either do `using OrdinaryDiffEqNonlinearSolve` or pass `initializealg = CheckInit()` to the `solve` function. This second option requires consistent `u0`.")
     else
         _initialize_dae!(integrator, prob,
             BrownFullBasicInit(integrator.opts.abstol), x)
@@ -81,10 +59,12 @@ function _initialize_dae!(integrator, prob::DAEProblem,
 end
 
 function _initialize_dae!(integrator, prob::DAEProblem,
-        alg::DefaultInit, x::Val{true})
+        alg::DefaultInit, x::Union{Val{true}, Val{false}})
     if SciMLBase.has_initializeprob(prob.f)
         _initialize_dae!(integrator, prob,
             OverrideInit(integrator.opts.abstol), x)
+    elseif !isdefined(Main, :OrdinaryDiffEqNonlinearSolve)
+        throw("`OrdinaryDiffEqNonlinearSolve` is not loaded, which is required for the default initialization algorithm (`BrownFullBasicInit` or `ShampineCollocationInit`). To solve this problem, either do `using OrdinaryDiffEqNonlinearSolve` or pass `initializealg = CheckInit()` to the `solve` function. This second option requires consistent `u0`.")
     elseif prob.differential_vars === nothing
         _initialize_dae!(integrator, prob,
             ShampineCollocationInit(), x)