I've updated using the documented method. It looks like this migration haven't run:
flarum/vendor/flarum/core/migrations/2015_02_24_000000_create_api_keys_table.php
And one line change in this migration is not applied:
extensions/tags/migrations/2015_02_24_000000_create_tags_table.php
change:
-$table->integer('last_time')->unsigned()->nullable();
+$table->dateTime('last_time')->nullable();
Am I doing something wrong?