Apple Store Connect 500 error when uploading app build

Apple Store Connect returning 500 error when trying to upload a new build of my app. Any idea why?

Error from network tab is:

{ "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/." }] }