ActiveRecord::UnknownAttributeError
unknown attribute: 1
app/controllers/subnets_controller.rb:74:in `create_multiple'
app/models/concerns/foreman/thread_session.rb:33:in `clear_thread'
lib/middleware/catch_json_parse_errors.rb:9:in `call'

It was dhcpd provider, but I don't think it's related.

One thing I forgot to mention is I was in context of an organization.
With 'any context' it didn't happen.