A common question with BaseElements and new releases is "How do I update to a new version of BaseElements".
About how BaseElements works
First as you can probably tell, BaseElements is just generic FileMaker files. And if you've worked in any way with data inside FileMaker files, there's no "simple" way to update a solution, although new tools ( data migration etc ) do help.
But on top of that, BaseElements has another unique issue that makes this a bit different. The data in BE is produced from the data in the Database Design Report. And a new version of BE will add new functionality where it pulls data from the DDR in a new way. So assuming you "update" BE, unless you re-import from the DDR then you won't have accurate information in one Analysis, compared to a new one. In the old import we didn't have this new feature. In the new version of BE we do, and so the two versions of your Analysis will be based on different interpretations of the data and one of them won't be accurate. To make this really clear :
One of the critical things that we've always tried to do is to make sure BE is super accurate. If I support a method to import data from old versions of BE into newer versions of BE then I'm supporting an approach that means you will have inaccurate data. And I don't ever want you to not trust the data in BE.
So I want to outline how I work with BE to not have to do data migrations. I just keep older versions of BE, I move them to an archive folder and I start fresh with the new version of BE. In situations where I want to look back at an older version of a solution Analysis, I open up my old copy of BE and just compare visually. This works because you can run two copies of BE at the same time with no issue. If I want to do something like run a comparison report, then I re-import from the old DDRs into the latest version of BE. To make that easier I keep my DDRs in folders where it's easy to go back to older versions and locate them. And if you have a choice, keeping the XML is better than keeping the BE versions as the XML text files compress really well, so a zipped folder of XML files will be much smaller than a zipped copy of BE with data imported from the XML.
I still want to migrate my old BE data into a new version
So you've read all of the above, and you're still keen to bring data across and you understand the issues. You can use the FileMaker Data Migration Tool to import data from one version of BE to another. You only need to migrate the BaseElements_19_Data.fmp12 file, the other files do not contain any useful migration data. There is an account and password in the Data file, that has the privileges set for Data Migration, called "dmt_import" and the password is the same. By default though, you shouldn't need it, the standard "User" account with no password allows access to the whole data set with no restrictions, and is the default account set in the File Options. If you've turned that account off as part of file sharing, then you may need to use the dmt_import.