Hi Shivakumar Subramanian (MSC Technology India),
This must related to AAD issue. The issue with AAD where only customers who are using MSA accounts are unable to login to Custom Vision portal. Currently, there is a workaround for this issue.
Create a new user in the tenant and grant this user as owner of the subscription.
Use this user to login to Azure portal for the first time.
Use this user to login to Custom Vision portal.
By doing so, the new created user is an AAD user and is not an MSA account. We are actively working to resolve the AAD issue to ensure the users who already had access can use the portal again.
It similar to other issues like,
Similar issues:
https://learn.microsoft.com/en-us/answers/questions/742929/customvisionai-whoops-we-can39t-seem-to-find-the-p.html?childToView=744351#comment-744351
https://learn.microsoft.com/en-us/answers/questions/742944/index.html
https://learn.microsoft.com/en-us/answers/questions/742999/index.html
https://learn.microsoft.com/en-us/answers/questions/744686/cannot-access-httpswwwcustomvisionai.html
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.