The following diagnostic is generating:

The California SOS number must be 12 numeric digits and start with a 19 or 20 when e-filing.  Please enter a valid SOS number in screen 1.

Solution:

Entity Number:
The identification number assigned to a business entity by the California Secretary of State at the time of registration. A corporation entity number is a 7 digit number with a C at the beginning. A limited liability company and limited partnership entity number is a 12 digit number with no letter at the beginning. 

This is a critical diagnostic and could be the difference between paper filing or electronic filing.