An Administrator is preparing to deploy change set into the production environment. Until the deployment is complete, only user with System Administrator profile should be allowed to access data in the production system. When any other user attempts to log in, a maintenance notice should be displayed instead. How can administrator meet this requirement

Assign all other users a custom profile with reading access to all objects revoked and add a custom homepage message

Explanation:

Until the deployment is complete, no user other than the user with System administrator profile should be allowed to access data in the production system.

In such a case, the administrator can assign all other users a custom profile with reading access to all objects revoked and add a custom homepage message.

i just joined so i'm not sure but you may need to verify your email if you haven't