Want to transport in as pattern ant attach products to each other to transport multiple. (Without using dummy product)
Error;
Process Node #307::ProcessExecutor__HIDE__::Process#1::Attach error: Expected process variable “ProductIn” to have value type “Ref” but the type is “List<Ref >”.
To add to what TSy said, the problem occurs if you use TransportPatternIn to get the parent part into the process. The TransportPatternIn creates a list of products, even if that list is only one product long. You should use TransportIn to get a single product.
The same happens if you use TransportIn to get multiple products to the same variable, so multiple products with variable name ProductIn for example.