Python Anytree - Is not of type 'NodeMixin' error

[Gribouillis]

will you be able to share few lines of code that will handle the issue

The anytree documentation about the «parent» attribute suggests that you can set the attribute after creation, so I suggest something like

nodes = {}
with open("SampleHierarchy.csv", "r") as f:
    # creation step
    csv_reader = csv.DictReader(f)
    for row in csv_reader:
        for item in (row['Code'], row['Parent']):
            if item and (item not in nodes):
                nodes[item] = Node(item)
    # parent setting step
    f.seek(0)
    csv_reader = csv.DictReader(f)
    for row in csv_reader:
        c, p = row['Code'], row['Parent']
        if c and p:
            nodes[c].parent = nodes[p]