Hi Amey Kale ,
Welcome to Microsoft Q&A platform and thanks for posting your question here.
As I understand your query, you are witnessing error in the child pipeline and it says "InternalServerError executing request" . Please let me know if that is not the correct understanding.
Kindly try executing the child pipeline independently to see if it runs successfully.
Additionally , please try checking the dataset and linked service used underneath the child pipeline is connected without any issue or not.
I suspect there is some issue with the source data . Kindly let us know how it goes.