I am also experiencing the same issue when trying to access the sales reports API in App Store Connect.
I received this message:
{
"errors": [
{
"status": "500",
"code": "UNEXPECTED_ERROR",
"title": "An unexpected error occurred.",
"detail": "An unexpected error occurred on the server side. If this issue continues, contact us at https://developer.apple.com/contact/."
}
]
}
It seems like there might be some kind of service disruption.
Hopefully, it will be resolved soon.