Why suddenly file upload not accepting files in Microsoft form?

Hi @Pradeep KUMAR SRIVASTAVA 1,

Thank you for posting on the Microsoft Q&A forum.

To help scope down the issue and identify the possible cause, could you provide a few additional details?

1. When did the issue first start occurring? Was it after any recent changes to SharePoint, OneDrive, Microsoft Forms, licensing, or permissions?
2. Does this affect all forms that use file upload, or only specific forms?
3. The users who are submitting files through the form, are they signing in with accounts from your organization, or are they external users (guest users or users outside your organization)? If both internal and external users are using the form, does the file upload issue affect both groups, or only one of them?
4. Are the forms configured to save uploaded files to a SharePoint document library or to the form owner's OneDrive for Business account?
5. Can you still see and access the linked folder where the files were previously being uploaded?
6. What exactly happens when users try to upload a file? Do they receive an error message, or is the upload option missing entirely? If there is an error, could you provide a screenshot (with any sensitive information removed)?
7. Have there been any recent changes to the form owner's account, such as a license change, account rename, account deletion, or ownership transfer?
8. Are you able to create a new test form with file upload enabled, and if so, does the same issue occur with the new form?

I apologize for asking several questions, but these details will help determine whether the issue is related to permissions, ownership, storage location changes, licensing, or another configuration issue.

Thank you for your patience and understanding. I look forward to your update.