This was due to an update in the underlying framework that runs DreamFactory.
This not a bug in a strict sense (there’s nothing to change in the code.) You just need a workaround to get past it.
You’ll see this issue if you go from pre-2.5 to 2.6 or later (I think those are the right versions.)
In your database, set the default value for those last_modified_date fields to CURRENT_TIMESTAMP and then run the migrations again. You may see this error for multiple tables. Repeat the process as needed.