# \`convert\` is ambiguous

**URL:** <https://discourse.julialang.org/t/convert-is-ambiguous/71192>\
**Category:** New to Julia\
**Created:** [November 9, 2021, 8:54am UTC](https://discourse.julialang.org/t/convert-is-ambiguous/71192 "2021-11-09T08:54:11Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![goerch](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/goerch/32/29122_2.png) [@goerch](https://discourse.julialang.org/u/goerch)\
**Post date:** [November 9, 2021, 8:54am UTC](https://discourse.julialang.org/t/convert-is-ambiguous/71192/1 "2021-11-09T08:54:11Z")

</div>

Surprising for me (Julia 1.6.3):

```julia
julia> a = [nothing]
1-element Vector{Nothing}:
 nothing

julia> a[1] = (0,)
ERROR: MethodError: convert(::Type{Union{}}, ::Tuple{Int64}) is ambiguous. Candidates:
  convert(::Type{T}, x::Tuple{Vararg{Any, N}}) where {N, T<:Tuple} in Base at essentials.jl:316
  convert(::Type{Union{}}, x) in Base at essentials.jl:203
  convert(::Type{T}, arg) where T<:VecElement in Base at baseext.jl:8
Possible fix, define
  convert(::Type{Union{}}, ::Tuple{Vararg{Any, N}}) where N

```

Is this expected? How can I fix it?

---

<div class="post-metadata">

**Author:** ![goerch](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/goerch/32/29122_2.png) [@goerch](https://discourse.julialang.org/u/goerch)\
**Post date:** [November 9, 2021, 8:57am UTC](https://discourse.julialang.org/t/convert-is-ambiguous/71192/2 "2021-11-09T08:57:57Z")

</div>

Nevermind. This works

```julia
julia> a = Union{Tuple{Int},Nothing}[nothing]
1-element Vector{Union{Nothing, Tuple{Int64}}}:
 nothing

julia> a[1] = (0,)
(0,)

```