# 4.x Upgrade Guide

## Breaking changes

### React version

No longer actively supporting React version < 16.3. The minimum supported version of React is now 16.3. [Discussion can be found here](https://github.com/rjsf-team/react-jsonschema-form/pull/2605#discussion_r792685354)

### @rjsf/material-ui package - Minimum version of material-ui 4

If you are using the material-ui 4 theme, @material-ui/core and @material-ui/icons packages should be updated to the latest versions. The minimum versions supported for @material-ui/core and @material-ui/icons are 4.12.0 and 4.11.1 respectively. This change is required for [support for the material-ui version 5 theme](https://github.com/rjsf-team/react-jsonschema-form/tree/main/packages/material-ui)
