Hello Chandrakant Pawle,
Welcome to microsoft Q&A, thankyou posting your query here.
Check if your image has tagged correctly .
Check if the credentials used are correct for registry
Check if your registry is private or public , if f the registry is private, make sure that the system identity of your online endpoint has the acrPull
role for the registry. You can grant this role using the Azure portal.
Private container registry is a registry that is only accessible to authorized users. Private registries are typically used by organizations to store and manage their own container images. Private registries provide more control over who can access the images and how they are used.
Hope this helps you.