Welcome!

When we try to issue E-Invoice, Odoo pop-out an error:

 File "/home/odoo/src/user/l10n_vn_viin_accounting_vninvoice/models/account_move.py", line 234, in _issue_vninvoice
    'TemplateNo': int(self._get_einvoice_template_name()),
Exception

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/odoo/src/odoo/odoo/http.py", line 658, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/home/odoo/src/odoo/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
ValueError: invalid literal for int() with base 10: '01GTKT0/001'

Seems the E-Invoice Template problem, however we follow your document to create the E-Invoice Template