If u go to orders then check checkbox near some order and then choose 'delete' there is a message:
'please first make a selection from the list'.
The workaround is to choose order status from 'Order status' combobox. Then click 'check all' from top menu. Then select 'delete'.
I have shop quite modified so if you could tell me how to fix this bug without update (I have version Version 4.2.1... I do not think last one brings sollution).
Thanks for help.