How do I show error messages in MUI?
You can use the AlertTitle component to display a formatted title above the content. This is an error alert — check it out! This is a warning alert — check it out!
What happened to material UI?
This package has been deprecated
Material UI v4 doesn't receive active development since September 2021. See the guide https://mui.com/material-ui/migration/migration-v4/ to upgrade to v5.