When I try to open a Sales Order, I get the An item with the same key has already been added error.
As the New Record button works, I was sure the extensions of DACs and Graph of Sales Orders screen do not contain any problematic code. Even more, the same error message can occur when there is no any package published.
Investigating the Generic Inquiry of SO3010PL, I found repetitive lines in Navigation Parameters section of NAVIGATION tab.
I still wonder how the duplicate lines could be added because when I try to add a record manually I get the The value of this field must be unique among all records. error. I decided to remove the repetitive lines. After that deletion, the SO3010PL GI allowed me to open the Sales Order Document via Order Nbr. field.
