Appraisal Error when creating

[khalloda]

Odoo version: 12.0-20181015
OpenHRMS: Latest on this gethub for v12

Odoo Server Error
Traceback (most recent call last):
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 653, in _handle_exception
return super(JsonRequest, self)._handle_exception(exception)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 312, in _handle_exception
raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\tools\pycompat.py", line 87, in reraise
raise value
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 695, in dispatch
result = self._call_function(**self.params)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 344, in _call_function
return checked_call(self.db, *args, **kwargs)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\service\model.py", line 97, in wrapper
return f(dbname, *args, **kwargs)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 337, in checked_call
result = self.endpoint(*a, **kw)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 938, in call
return self.method(*args, **kw)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 517, in response_wrap
response = f(*args, **kw)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\addons\web\controllers\main.py", line 962, in call_kw
return self._call_kw(model, method, args, kwargs)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\addons\web\controllers\main.py", line 954, in _call_kw
return call_kw(request.env[model], method, args, kwargs)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\api.py", line 745, in call_kw
return _call_kw_model(method, model, args, kwargs)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\api.py", line 718, in _call_kw_model
result = method(recs, *args, **kwargs)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\models.py", line 1151, in default_get
defaults = self._convert_to_write(defaults)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\models.py", line 4752, in _convert_to_write
value = field.convert_to_cache(value, self, validate=False)
File "C:\Program Files (x86)\Odoo 12.0\server\odoo\fields.py", line 1605, in convert_to_cache
raise TypeError("%s (field %s) must be string or date, not datetime." % (value, self))
TypeError: 2018-11-07 12:58:09 (field hr.appraisal.app_period_from) must be string or date, not datetime.