Robokassa shows an "Incorrect parameter: InvoiceID" error. What is wrong and how to resolve the issue?
This error occurs because of the restrictions on the Robokassa service's side. According to the Robokassa documentation, the order number can only be numerical between 1 and 2147483647.
In Magento the order incremental id can be larger. Also some 3rd party extensions can change the incremental id format to a non-numeric one.
For simpler order identification (transactions in the Robokassa service and orders in the site's admin account) the extension uses the order increment id by default, due to that the internal id is not displayed anywhere in admin.
You can start using the order internal id, by changing the following option in the extension configuration file /app/code/community/ET/PaymentRobokassa/etc/config.xml
<invoice_id_type>0</invoice_id_type> => <invoice_id_type>1</invoice_id_type>