I duplicate a package and change ftp preprod to ftp prod /
It's working well and i have my mapping with external id,
But i run the package i have the error "An exception has occurred during upsert operation, the message returned from the provider is: To be able to 'UPSERT' records one of the columns should be marked as 'ExternalId'."
And when i look the mapping external id is not save
Can you look this ? (because i need to do that for all packages)