Is there some possibility to seed admin accounts? Because when I create Seeder file in my plugin updates directory and run october:up, it fails, because admin group doesn't exist yet.

You can run the seeder code via the PHP code section of any page, I suppose.

Where do you see the error, is it using the CLI or GUI installer?

I'm using CLI and it fails because when I run my plugin migration (with empty database using october:up), there is no Admin group created in database. It seems that CMS seed runs on the end, after plugins migrations.

But I realize, that seeding aplication from plugin is not great idea, so I created admins manually.

Thanks for reply!