First, I want to say thank you.

Second, I want to say that I am getting conflicting information from Quickbooks sources.  I have data files in 2008 and 2012 formats.  After some of the answers on this thread, I went looking for sources to download the "trial" versions of 2015, 2016, 2018, etc. but did not find them on the Intuit site.  Then I went with Google and searched but did not find them either.   Yet, repeatedly I was fold I had to migrate through perhaps 2 prior versions before going to 2021. 

Third, I got frustrated and again called Intuit.  I had someone on the phone and they said the same thing - need to migrate through prior editions.  But, when he went to give me the links they were no longer good.  Even he said he did not know where to find them.  

Fourth, I requested a callback through QB2021 for installation help.  I finally got a call back after a few attempts and this person said you do not have to migrate through prior editions that QB2021 should handle it.  I made a backup of the QB2012 file, moved it to a new directory, and tried to do a restore.  It finally ran but I have no way to know if its complete or accurate. In fact, I am assuming that the SOFTWARE DEVELOPER's recommendation of migrations is because the data structure changes with each edition and there is a need for those intermediate modifications to be made or important tables or fields will be missing. 

Fifth, if there is a need for a migration path and QB built its system to require it then either a utility or some version of software necessary for that process should exist and everyone should be on the same page about what it is.