diff --git a/base/namedtuple.jl b/base/namedtuple.jl
index e489508bc55ea..37514ec450013 100644
--- a/base/namedtuple.jl
+++ b/base/namedtuple.jl
@@ -183,16 +183,15 @@ nextind(@nospecialize(t::NamedTuple), i::Integer) = Int(i)+1
 convert(::Type{NT}, nt::NT) where {names, NT<:NamedTuple{names}} = nt
 convert(::Type{NT}, nt::NT) where {names, T<:Tuple, NT<:NamedTuple{names,T}} = nt
 
-function convert(::Type{NT}, nt::NamedTuple{names}) where {names, T<:Tuple, NT<:NamedTuple{names,T}}
-    if !@isdefined T
-        # converting abstract NT to an abstract Tuple type, to a concrete NT1, is not straightforward, so this could just be an error, but we define it anyways
-        # _tuple_error(NT, nt)
-        T1 = Tuple{ntuple(i -> fieldtype(NT, i), Val(length(names)))...}
-        NT1 = NamedTuple{names, T1}
-    else
-        T1 = T
-        NT1 = NT
-    end
+function convert(::Type{NamedTuple{names,T}}, nt::NamedTuple{names}) where {names,T<:Tuple}
+    NamedTuple{names,T}(T(nt))::NamedTuple{names,T}
+end
+
+function convert(::Type{NT}, nt::NamedTuple{names}) where {names, NT<:NamedTuple{names}}
+    # converting abstract NT to an abstract Tuple type, to a concrete NT1, is not straightforward, so this could just be an error, but we define it anyways
+    # _tuple_error(NT, nt)
+    T1 = Tuple{ntuple(i -> fieldtype(NT, i), Val(length(names)))...}
+    NT1 = NamedTuple{names, T1}
     return NT1(T1(nt))::NT1::NT
 end
 
diff --git a/src/subtype.c b/src/subtype.c
index efff6218dfb71..c67beecae9dbd 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -941,8 +941,8 @@ static int subtype_unionall(jl_value_t *t, jl_unionall_t *u, jl_stenv_t *e, int8
             jl_value_t *vl = btemp->lb;
             // TODO: this takes a significant amount of time
             if (btemp->depth0 != vb.depth0 &&
-                ((vu != (jl_value_t*)vb.var && btemp->var->ub != vu && var_occurs_invariant(vu, vb.var)) ||
-                 (vl != (jl_value_t*)vb.var && btemp->var->lb != vl && var_occurs_invariant(vl, vb.var)))) {
+                ((vu != (jl_value_t*)vb.var && btemp->var->ub != vu && var_occurs_inside(vu, vb.var, 0, 0)) ||
+                 (vl != (jl_value_t*)vb.var && btemp->var->lb != vl && var_occurs_inside(vl, vb.var, 0, 0)))) {
                 ans = 0; break;
             }
             btemp = btemp->prev;
diff --git a/stdlib/LinearAlgebra/src/bidiag.jl b/stdlib/LinearAlgebra/src/bidiag.jl
index 756b991c72a07..fcb098a005510 100644
--- a/stdlib/LinearAlgebra/src/bidiag.jl
+++ b/stdlib/LinearAlgebra/src/bidiag.jl
@@ -214,7 +214,7 @@ Matrix(A::Bidiagonal{T}) where {T} = Matrix{promote_type(T, typeof(zero(T)))}(A)
 Array(A::Bidiagonal) = Matrix(A)
 promote_rule(::Type{Matrix{T}}, ::Type{<:Bidiagonal{S}}) where {T,S} =
     @isdefined(T) && @isdefined(S) ? Matrix{promote_type(T,S)} : Matrix
-promote_rule(::Type{Matrix}, ::Type{<:Bidiagonal}) = Matrix
+promote_rule(::Type{<:Matrix}, ::Type{<:Bidiagonal}) = Matrix
 
 #Converting from Bidiagonal to Tridiagonal
 function Tridiagonal{T}(A::Bidiagonal) where T
diff --git a/test/subtype.jl b/test/subtype.jl
index 19901897ebaaa..a57ee2f23cb9b 100644
--- a/test/subtype.jl
+++ b/test/subtype.jl
@@ -1436,6 +1436,9 @@ struct A23764_2{T, N, S} <: AbstractArray{Union{Ref{T}, S}, N}; end
 @test Tuple{A23764_2{T, 1, Nothing} where T} <: Tuple{AbstractArray{T,N}} where {T,N}
 @test Tuple{A23764_2{T, 1, Nothing} where T} <: Tuple{AbstractArray{T,N} where {T,N}}
 
+# issue #50716
+@test !<:(Ref{Vector{Tuple{K}} where K}, Ref{<:Vector{K}} where K)
+
 # issue #26131
 @test !(Vector{Vector{Number}} <: Vector{Union{Vector{Number}, Vector{S}}} where S<:Integer)