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docs/data/system/migration/upgrade-to-v7/upgrade-to-v7.md

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+# Upgrade to v7
+
+<p class="description">This guide explains how to upgrade from MUI System v6 to v7.</p>
+
+## Breaking changes
+
+Since v7 is a new major release, it contains some changes that affect the public API.
+The steps you need to take to migrate from MUI System v6 to v7 are described below.
+
+### Package layout
+
+The package layout has been updated to use the Node.js exports field. This brings several changes:
+
+Deep imports with more than one level are no longer working, at all (they were already considered private API). For example:
+
+```diff
+-import Box from '@mui/system/Box/Box';
++import Box from '@mui/system/Box';
+```
+
+This was never officially supported, but will now be restricted by bundlers and runtimes.
+
+To use the modern bundle (which excludes legacy browser support for smaller bundle size), you'll need to configure your bundler to use the "mui-modern" exports condition:
+
+```js
+// webpack.config.js
+{
+  resolve: {
+    conditionNames: ['mui-modern', '...'],
+  }
+}
+
+// vite.config.js
+{
+  resolve: {
+    conditions: ['mui-modern', 'module', 'browser', 'development|production']
+  }
+}
+```