Error: ‘ir.mail_server’ object has no attribute ‘keep_days’ while selecting outgoing mail server in invoice template

Summary

I am trying to send invoices per email. I have 2 working outgoing email servers configured. If I try to configure the invoice email template and select the outgoing email server on advanced settings tab, I get the following error.

Error Traceback: Traceback (most recent call last): File “/usr/lib/python3/dist-packages/flectra/http.py”, line 653, in _handle_exception return super(JsonRequest, self)._handle_exception(exception) File “/usr/lib/python3/dist-packages/flectra/http.py”, line 312, in _handle_exception raise pycompat.reraise(type(exception), exception, sys.exc_info()[2]) File “/usr/lib/python3/dist-packages/flectra/tools/pycompat.py”, line 87, in reraise raise value File “/usr/lib/python3/dist-packages/flectra/http.py”, line 695, in dispatch result = self._call_function(**self.params) File “/usr/lib/python3/dist-packages/flectra/http.py”, line 344, in _call_function return checked_call(self.db, *args, **kwargs) File “/usr/lib/python3/dist-packages/flectra/service/model.py”, line 97, in wrapper return f(dbname, *args, **kwargs) File “/usr/lib/python3/dist-packages/flectra/http.py”, line 337, in checked_call result = self.endpoint(*a, **kw) File “/usr/lib/python3/dist-packages/flectra/http.py”, line 939, in call return self.method(*args, **kw) File “/usr/lib/python3/dist-packages/flectra/http.py”, line 517, in response_wrap response = f(*args, **kw) File “/usr/lib/python3/dist-packages/flectra/addons/web/controllers/main.py”, line 1090, in call_kw return self._call_kw(model, method, args, kwargs) File “/usr/lib/python3/dist-packages/flectra/addons/web/controllers/main.py”, line 1082, in _call_kw return call_kw(request.env[model], method, args, kwargs) File “/usr/lib/python3/dist-packages/flectra/api.py”, line 689, in call_kw return call_kw_multi(method, model, args, kwargs) File “/usr/lib/python3/dist-packages/flectra/api.py”, line 680, in call_kw_multi result = method(recs, *args, **kwargs) File “/usr/lib/python3/dist-packages/flectra/models.py”, line 5195, in onchange record._onchange_eval(name, field_onchange[name], result) File “/usr/lib/python3/dist-packages/flectra/models.py”, line 5021, in _onchange_eval method_res = method(self) File “/usr/lib/python3/dist-packages/flectra/addons/mail/models/mail_template.py”, line 213, in onchange_mail_server_id if self.mail_server_id and self.mail_server_id.keep_days > 0 AttributeError: ‘ir.mail_server’ object has no attribute ‘keep_days’

Steps to reproduce

1. Open an invoice and select "send by eMail"
2. Open eMail template on the right side
3. Select tab "Advanced settings"
4. Select an outgoing eMail server -> above error is shown

What is the current bug behavior?

Error message shown that object ‘ir.mail_server’ has no attribute ‘keep_days’

What is the expected correct behavior?

Outgoing eMail server should be saved as default mail server.

Relevant logs and/or screenshots

see above

Possible fixes

Add attribute "keep_days" to object "ir.mail_server".

Adding a user specific attribute does not work, since user specfic attributes need to start with "x_".