Odoo migration to v16: Error for standard wizard

When i try to install my -originally in v13 developed custom module- in Odoo v16-apps, i got an error, even for an empty wizard (with a structure which is identical the other wizards definitions found in the official odoo addons)!:

But, even if i have tried to reduce my wizard definition to the minimalist content, i keep on getting this error on install:

**File "/home/odoo/src/odoo/odoo/tools/convert.py", line 711, in _tag_root
    raise ParseError('while parsing %s:%s, somewhere inside\n%s' % (
odoo.tools.convert.ParseError: while parsing /home/odoo/src/user/my_custom_module_zsb/wizard/my_custom_wizard.xml:3, somewhere inside**

Traceback:

Failed to load registry
Traceback (most recent call last):
  File "/home/odoo/src/odoo/odoo/tools/convert.py", line 698, in _tag_root
    f(rec)
  File "/home/odoo/src/odoo/odoo/tools/convert.py", line 599, in _tag_record
    record = model._load_records([data], self.mode == 'update')
  File "/home/odoo/src/odoo/odoo/models.py", line 4364, in _load_records
    data['record']._load_records_write(data['values'])
  File "/home/odoo/src/odoo/odoo/addons/base/models/ir_ui_view.py", line 2218, in _load_records_write
    super(View, self)._load_records_write(values)
  File "/home/odoo/src/odoo/odoo/models.py", line 4295, in _load_records_write
    self.write(values)
  File "/home/odoo/src/odoo/addons/website/models/theme_models.py", line 385, in write
    res = super(IrUiView, other_views).write(vals)
  File "/home/odoo/src/odoo/addons/website/models/ir_ui_view.py", line 93, in write
    return super(View, self).write(vals)
  File "/home/odoo/src/enterprise/web_studio/models/studio_mixin.py", line 33, in write
    res = super(StudioMixin, self).write(vals)
  File "/home/odoo/src/odoo/odoo/addons/base/models/ir_ui_view.py", line 573, in write
    res = super(View, self).write(self._compute_defaults(vals))
  File "/home/odoo/src/odoo/odoo/models.py", line 3787, in write
    fields[0].determine_inverse(real_recs)
  File "/home/odoo/src/odoo/odoo/fields.py", line 1396, in determine_inverse
    determine(self.inverse, records)
  File "/home/odoo/src/odoo/odoo/fields.py", line 97, in determine
    return needle(*args)
  File "/home/odoo/src/odoo/odoo/addons/base/models/ir_ui_view.py", line 340, in _inverse_arch
    view.write(data)
  File "/home/odoo/src/odoo/addons/website/models/theme_models.py", line 385, in write
    res = super(IrUiView, other_views).write(vals)
  File "/home/odoo/src/odoo/addons/website/models/ir_ui_view.py", line 93, in write
    return super(View, self).write(vals)
  File "/home/odoo/src/enterprise/web_studio/models/studio_mixin.py", line 33, in write
    res = super(StudioMixin, self).write(vals)
  File "/home/odoo/src/odoo/odoo/addons/base/models/ir_ui_view.py", line 573, in write
    res = super(View, self).write(self._compute_defaults(vals))
  File "/home/odoo/src/odoo/odoo/models.py", line 3755, in write
    field.write(self, value)
  File "/home/odoo/src/odoo/odoo/fields.py", line 1815, in write
    text2terms[self.get_text_content(term)].append(term)
  File "/home/odoo/src/odoo/odoo/fields.py", line 1681, in get_text_content
    return func(term)
  File "/home/odoo/src/odoo/odoo/tools/translate.py", line 361, in get_text_content
    content = html.fromstring(term).text_content()
  File "/usr/lib/python3/dist-packages/lxml/html/__init__.py", line 875, in fromstring
    doc = document_fromstring(html, parser=parser, base_url=base_url, **kw)
  File "/usr/lib/python3/dist-packages/lxml/html/__init__.py", line 763, in document_fromstring
    raise etree.ParserError(
lxml.etree.ParserError: Document is empty

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/odoo/src/odoo/odoo/modules/registry.py", line 90, in new
    odoo.modules.load_modules(registry, force_demo, status, update_module)
  File "/home/odoo/src/odoo/odoo/modules/loading.py", line 484, in load_modules
    processed_modules += load_marked_modules(cr, graph,
  File "/home/odoo/src/odoo/odoo/modules/loading.py", line 372, in load_marked_modules
    loaded, processed = load_module_graph(
  File "/home/odoo/src/odoo/odoo/modules/loading.py", line 231, in load_module_graph
    load_data(cr, idref, mode, kind='data', package=package)
  File "/home/odoo/src/odoo/odoo/modules/loading.py", line 71, in load_data
    tools.convert_file(cr, package.name, filename, idref, mode, noupdate, kind)
  File "/home/odoo/src/odoo/odoo/tools/convert.py", line 763, in convert_file
    convert_xml_import(cr, module, fp, idref, mode, noupdate)
  File "/home/odoo/src/odoo/odoo/tools/convert.py", line 829, in convert_xml_import
    obj.parse(doc.getroot())
  File "/home/odoo/src/odoo/odoo/tools/convert.py", line 749, in parse
    self._tag_root(de)
  File "/home/odoo/src/odoo/odoo/tools/convert.py", line 711, in _tag_root
    raise ParseError('while parsing %s:%s, somewhere inside\n%s' % (
odoo.tools.convert.ParseError: while parsing /home/odoo/src/user/my_custom_module_zsb/wizard/my_custom_wizard.xml:3, somewhere inside
  
    my.custom.wizard.form
    
How to change my wizard or the way to call it to match the odoo 16 requirements ?