Where are the primary and secondary tab blocks? I installed drupal 8 using the minimal install profile. For the admin pages I enabled the seven admin theme, but in the blocks admin screen I cannot find the Primary tabs and Secondary tabs blocks.
They are available under other names (I think one is called "Tabs") when you used the the minimal installation profile. 

But you can import the blocks by entering the code of the files

profiles/standard/config/install/block.block.seven_primary_local_tasks.yml
profiles/standard/config/install/block.block.seven_secondary_local_tasks.yml 


into the Single config import located at 

admin/config/development/configuration/single/import


(this requires the config management module to be enabled)