now i solved the problem.
I changed my controller method to:
def printing
@bills = Bill.find(params[:id])
respond_to do |format|
format.html
format.pdf do
render :pdf => "bill_#{@bills.id}",
:wkhtmltopdf => '/usr/bin/wkhtmltopdf',
:template => '/bills/printing.pdf.erb',
:disposition => "inline"
#:save_to_file => Rails.root.join('pdf', "rechnung_#{@bills.id}.pdf")
end
end
end
and i had to remove WickedPDF as middleware in the application.rb:
require 'wicked_pdf'
config.middleware.use WickedPdf::Middleware, {}
now it's working as expected.