If you encountered issues uploading your photo ID for the AZ-900 exam and were unable to take the test, your recourse would be to contact Microsoft Exam Accommodations for assistance. They can help you with the situation regarding your exam and any potential rescheduling or refund options. You should reach out to them as soon as possible to explain your circumstances and seek a resolution.
Additionally, if you have already missed your exam time, it’s important to follow up with the scheduling agent mentioned in your original approval letter to discuss rescheduling your exam.
References: