Error: Odoo Server Error Traceback (most recent call last): File "/opt/odoo/odoo/odoo/http.py", line 653, in _handle_exception return super(JsonRequest, self)._handle_exception(exception) File "/opt/odoo/odoo/odoo/http.py", line 312, in _handle_exception raise pycompat.reraise(type(exception), exception, sys.exc_info()[2]) File "/opt/odoo/odoo/odoo/tools/pycompat.py", line 87, in reraise raise value File "/opt/odoo/odoo/odoo/http.py", line 695, in dispatch result = self._call_function(**self.params) File "/opt/odoo/odoo/odoo/http.py", line 344, in _call_function return checked_call(self.db, *args, **kwargs) File "/opt/odoo/odoo/odoo/service/model.py", line 97, in wrapper return f(dbname, *args, **kwargs) File "/opt/odoo/odoo/odoo/http.py", line 337, in checked_call result = self.endpoint(*a, **kw) File "/opt/odoo/odoo/odoo/http.py", line 939, in __call__ return self.method(*args, **kw) File "/opt/odoo/odoo/odoo/http.py", line 517, in response_wrap response = f(*args, **kw) File "/opt/odoo/odoo/addons/web/controllers/main.py", line 938, in call_button action = self._call_kw(model, method, args, {}) File "/opt/odoo/odoo/addons/web/controllers/main.py", line 926, in _call_kw return call_kw(request.env[model], method, args, kwargs) File "/opt/odoo/odoo/odoo/api.py", line 699, in call_kw return call_kw_multi(method, model, args, kwargs) File "/opt/odoo/odoo/odoo/api.py", line 690, in call_kw_multi result = method(recs, *args, **kwargs) File "/opt/odoo/odoo/addons/invoice_dotmatrix_printer/models/account.py", line 19, in print_new_receipt data = templ.render_template(templ.body_html, 'account.invoice', self.id) AttributeError: 'mail.template' object has no attribute '_render_template'

hi i purchased the app and i cannot find the doenload link for odoo 11. it just shows odoo 12 only