julia> using Krylov, SparseArrays

julia> A = rand(4, 4);

julia> b = reshape(sparse(rand(2, 2)), 4);

julia> A \ b
4-element Vector{Float64}:
  1.2848205878872323
  1.3981946106958438
 -1.5218841143490067
 -0.7467704138939663

julia> gmres(A, b)
ERROR: MethodError: no method matching Base.ReshapedArray{Float64, 1, SparseMatrixCSC{Float64, Int64}, Tuple{Base.MultiplicativeInverses.SignedMultiplicativeInverse{Int64}}}(::UndefInitializer, ::Int64)

Closest candidates are:
  (::Type{Base.ReshapedArray{T, N, P, MI}} where {T, N, P<:AbstractArray, MI<:Tuple{Vararg{Base.MultiplicativeInverses.SignedMultiplicativeInverse{Int64}}}})(::Any, ::Any, ::Any)
   @ Base reshapedarray.jl:6

Stacktrace:
 [1] GmresSolver(m::Int64, n::Int64, memory::Int64, S::Type{Base.ReshapedArray{Float64, 1, SparseMatrixCSC{Float64, Int64}, Tuple{Base.MultiplicativeInverses.SignedMultiplicativeInverse{Int64}}}})
   @ Krylov ~/Work/GitHub/Julia/Krylov.jl/src/krylov_solvers.jl:1549
 [2] GmresSolver(A::Matrix{Float64}, b::Base.ReshapedArray{Float64, 1, SparseMatrixCSC{Float64, Int64}, Tuple{Base.MultiplicativeInverses.SignedMultiplicativeInverse{Int64}}}, memory::Int64)
   @ Krylov ~/Work/GitHub/Julia/Krylov.jl/src/krylov_solvers.jl:1567
 [3] gmres(A::Matrix{Float64}, b::Base.ReshapedArray{Float64, 1, SparseMatrixCSC{Float64, Int64}, Tuple{Base.MultiplicativeInverses.SignedMultiplicativeInverse{Int64}}}; memory::Int64, M::LinearAlgebra.UniformScaling{Bool}, N::LinearAlgebra.UniformScaling{Bool}, ldiv::Bool, restart::Bool, reorthogonalization::Bool, atol::Float64, rtol::Float64, itmax::Int64, timemax::Float64, verbose::Int64, history::Bool, callback::Krylov.var"#164#171", iostream::Core.CoreSTDOUT)
   @ Krylov ~/Work/GitHub/Julia/Krylov.jl/src/gmres.jl:121
 [4] gmres(A::Matrix{Float64}, b::Base.ReshapedArray{Float64, 1, SparseMatrixCSC{Float64, Int64}, Tuple{Base.MultiplicativeInverses.SignedMultiplicativeInverse{Int64}}})
   @ Krylov ~/Work/GitHub/Julia/Krylov.jl/src/gmres.jl:119
 [5] top-level scope
   @ REPL[6]:1