Internal Server Error during the initial setup

I have a brand new ERPNext install, on a new CentOS 7.
Used ‘easy Install’ option. Scripts executed successfully.

I can log in as Administrator and start the setup wizard, but after I enter all the required data and get to ‘Setting up your system’ message, I get an ‘internal server error’.
Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 61, in application
response = frappe.handler.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 21, in handle
data = execute_cmd(cmd)
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 56, in execute_cmd
return, **frappe.form_dict)
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 1019, in call
return fn(*args, **newargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/core/doctype/user/”, line 787, in sign_up
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/”, line 249, in insert
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/”, line 905, in run_post_save_methods
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/”, line 772, in run_method
out = Document.hook(fn)(self, *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/”, line 1048, in composer
return composed(self, method, *args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/”, line 1031, in runner
add_to_return_value(self, fn(self, *args, **kwargs))
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/”, line 766, in
fn = lambda self, *args, **kwargs: getattr(self, method)(*args, **kwargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/core/doctype/user/”, line 95, in on_update
File “/home/frappe/frappe-bench/apps/frappe/frappe/core/doctype/user/”, line 203, in send_password_notification
File “/home/frappe/frappe-bench/apps/frappe/frappe/core/doctype/user/”, line 269, in send_welcome_mail_to_user
File “/home/frappe/frappe-bench/apps/frappe/frappe/core/doctype/user/”, line 295, in send_login_mail
delayed=(not now) if now!=None else self.flags.delay_emails, retry=3)
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 463, in sendmail
inline_images=inline_images, header=header, print_letterhead=print_letterhead)
File “/home/frappe/frappe-bench/apps/frappe/frappe/email/”, line 71, in send
sender = email_account.default_sender
AttributeError: ‘NoneType’ object has no attribute ‘default_sender’
[ERROR] 2019-02-06 15:07:02,802 | /home/frappe/frappe-bench/apps/frappe/frappe/utils/
New Exception collected with id: 2019-02-06 15:07:02.444600-

Looks like it dies on not having a default email set up, but as it dies on initial setup, I have no idea how to fix it. Except maybe by entering it directly into the database, but I don’t know enough about the system to try that.

Any advice much appreciated!

In case anyone else gets the same problem…
Install bench manager
Change default site (frappe-bench/sites/currentsite.txt), log into bench manager, create default outgoing email.
Change default site back, log in as Administrator, and all is good

may can help