Storefront GraphQL cartLinesAdd API not working

Below is the response I am getting when hitting this API:

{
“data”: {
“cartLinesAdd”: null
},
“errors”: [
{
“message”: “invalid id”,
“locations”: [
{
“line”: 3,
“column”: 3
}
],
“path”: [
“cartLinesAdd”
]
}
]
}

Can you please check what’s wrong here?

Can anyone please help me to fix this issue?