I'm trying to install the module Stock but I'm getting this error:

Traceback (most recent call last):
  File "/opt/odoo12/hts20/odoo/http.py", line 656, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/opt/odoo12/hts20/odoo/http.py", line 314, in _handle_exception
    raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
  File "/opt/odoo12/hts20/odoo/tools/pycompat.py", line 87, in reraise
    raise value
  File "/opt/odoo12/hts20/odoo/http.py", line 698, in dispatch
    result = self._call_function(**self.params)
  File "/opt/odoo12/hts20/odoo/http.py", line 346, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/opt/odoo12/hts20/odoo/service/model.py", line 98, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/odoo12/hts20/odoo/http.py", line 339, in checked_call
    result = self.endpoint(*a, **kw)
  File "/opt/odoo12/hts20/odoo/http.py", line 941, in __call__
    return self.method(*args, **kw)
  File "/opt/odoo12/hts20/odoo/http.py", line 519, in response_wrap
    response = f(*args, **kw)
  File "/opt/odoo12/hts20/addons/web/controllers/main.py", line 967, in call_button
    action = self._call_kw(model, method, args, {})
  File "/opt/odoo12/hts20/addons/web/controllers/main.py", line 955, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/opt/odoo12/hts20/odoo/api.py", line 759, in call_kw
    return _call_kw_multi(method, model, args, kwargs)
  File "/opt/odoo12/hts20/odoo/api.py", line 746, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "", line 2, in button_immediate_install
  File "/opt/odoo12/hts20/odoo/addons/base/models/ir_module.py", line 74, in check_and_log
    return method(self, *args, **kwargs)
  File "/opt/odoo12/hts20/odoo/addons/base/models/ir_module.py", line 445, in button_immediate_install
    return self._button_immediate_function(type(self).button_install)
  File "/opt/odoo12/hts20/odoo/addons/base/models/ir_module.py", line 561, in _button_immediate_function
    modules.registry.Registry.new(self._cr.dbname, update_module=True)
  File "/opt/odoo12/hts20/odoo/modules/registry.py", line 86, in new
    odoo.modules.load_modules(registry._db, force_demo, status, update_module)
  File "/opt/odoo12/hts20/odoo/modules/loading.py", line 419, in load_modules
    processed_modules += load_marked_modules(cr, graph,
  File "/opt/odoo12/hts20/odoo/modules/loading.py", line 311, in load_marked_modules
    loaded, processed = load_module_graph(
  File "/opt/odoo12/hts20/odoo/modules/loading.py", line 179, in load_module_graph
    load_openerp_module(package.name)
  File "/opt/odoo12/hts20/odoo/modules/module.py", line 368, in load_openerp_module
    __import__('odoo.addons.' + module_name)
  File "", line 991, in _find_and_load
  File "", line 975, in _find_and_load_unlocked
  File "", line 655, in _load_unlocked
  File "", line 618, in _load_backward_compatible
  File "/opt/odoo12/hts20/odoo/modules/module.py", line 82, in load_module
    exec(open(modfile, 'rb').read(), new_mod.__dict__)
  File "", line 4, in 
  File "/opt/odoo12/hts20/addons/product/models/__init__.py", line 12, in 
    from . import product
  File "/opt/odoo12/hts20/addons/product/models/product.py", line 735, in 
    class SupplierInfo(models.Model):
  File "/opt/odoo12/hts20/addons/product/models/product.py", line 769, in SupplierInfo
    date_start = fields.Date('Start Date', help="Start date for this vendor price")
TypeError: 'Date' object is not callable

This is happening when I try to install any module that contains a Date field.