Economic.Api.Exceptions.ServerException(E00000): An internal error has occurred. (id=c493bfe1-0d56-4abc-a009-297ceddec2a6)
This type of Internal Exceptions are comes when , In the service method array expecting something but we are sending the data not correctly.So, Mismatching of data occurs, In your case you are sended the product data to service, But tha array can store in the for of index based.
"Number" = > $product_id,
"ProductGroupHandle" = >array("Number" => $ProductGroupHandle),
similarly all properties Dynamically,
I think you got all $product_data info...
Main problem you got when you call Product_CreateFromData service,
The short solution for that is ,
$res = $this->client->Product_CreateFromData(array("number" =>1, "data"=>$productdata));
Here you dont get Number and Internal Exceptions.
This is perfectly Works when you got $product_data Perfectly.
if is not works feel free to ask me.