I got above error when I select the company and account in the customer.
I am using V 11.1.14
thanks for sharing. There are some issues in v11 regarding multi-company, e.g. https://github.com/frappe/erpnext/issues/16958. I am not sure if this is related, though. “The resource you are looking for is not available” with Company None makes sense, it checks for a company None, which does not exist…
I have tried to reproduce this in a ERPNext: v11.1.18, and it allows me to save. Maybe try to upgrade?
Take a look at ‘Global Defaults’, see if ‘Default Company’ has a value, shouldn’t be blank.