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Documentation

Upgrading from Early Hilla Versions

The steps to upgrade from Hilla 1.x or 2.x to the latest version.

Upgrading to the latest version of Hilla is an excellent idea. It allows you to take advantage of all that Hilla has to offer. On this page are two major sections: upgrading from 2.x to 24.4.0, which is covered in the next section; and upgrading from Hilla 1.x from Hilla 2.0, which is explained in the subsequent major section.

Upgrading from 2.x to 24.4.0

Upgrading from Hilla 2.x to 24.4.0 involves several important steps across different parts of a project. This guide provides detailed instructions to ensure a smooth transition, covering changes from build configurations to source code adjustments.

It may take some time, but upgrading to Vaadin 24.4.0 means your project will utilize the new Vaadin Unified Platform, not just the Hilla framework.

Note
Changes in Build Related Files
Regardless of how you build your project, the changes listed below are relevant to all Hilla projects. However, when it comes to changes in build-related files, you can refer to Maven Projects: pom.xml Changes or Gradle Projects: Configuration Changes, according to the type of build tool you use.

Maven Projects: pom.xml Changes

To update your Maven project to use Vaadin 24.4.0, you’ll need to adjust your pom.xml as explained in each step that follows.

Rename hilla.version Property

Update the property name that defines the framework version, from hilla.version property to vaadin.version. Then set its value to 24.4.x, or rather the version you’re using. This change ensures that all subsequent dependencies use the correct version variable:

<properties>
-    <hilla.version>2.x</hilla.version>
+    <vaadin.version>24.4.0</vaadin.version>
</properties>

Replace Hilla BOM with Vaadin BOM

Change the Bill of Materials (BOM) from Hilla to Vaadin. This will ensure that your project uses compatible versions of Vaadin libraries:

<dependencyManagement>
    <dependencies>
-        <dependency>
-            <groupId>dev.hilla</groupId>
-            <artifactId>hilla-bom</artifactId>
-            <version>${hilla.version}</version>
-            <type>pom</type>
-            <scope>import</scope>
-        </dependency>
+        <dependency>
+            <groupId>com.vaadin</groupId>
+            <artifactId>vaadin-bom</artifactId>
+            <version>${vaadin.version}</version>
+            <type>pom</type>
+            <scope>import</scope>
+        </dependency>
    </dependencies>
</dependencyManagement>

Update Hilla Core Dependency

Replace the core Hilla library dependency with the equivalent Vaadin library:

<dependencies>
-    <dependency>
-        <groupId>dev.hilla</groupId>
-        <artifactId>hilla</artifactId>
-    </dependency>
+    <dependency>
+        <groupId>com.vaadin</groupId>
+        <artifactId>vaadin</artifactId>
+    </dependency>
</dependencies>

Update Spring Boot Starter for Hilla

Change the Hilla Spring Boot starter dependency to Vaadin’s Spring Boot starter:

<dependencies>
-    <dependency>
-        <groupId>dev.hilla</groupId>
-        <artifactId>hilla-spring-boot-starter</artifactId>
-    </dependency>
+    <dependency>
+        <groupId>com.vaadin</groupId>
+        <artifactId>vaadin-spring-boot-starter</artifactId>
+    </dependency>
</dependencies>

Handle React-Spring Boot Starter

Ensure that any React-specific Spring Boot starters are also updated:

<dependencies>
-    <dependency>
-        <groupId>dev.hilla</groupId>
-        <artifactId>hilla-react-spring-boot-starter</artifactId>
-    </dependency>
+    <dependency>
+        <groupId>com.vaadin</groupId>
+        <artifactId>vaadin-spring-boot-starter</artifactId>
+    </dependency>
</dependencies>

Replace the Hilla Maven Plugin

Switch the Maven plugin from Hilla to Vaadin to use Vaadin’s build plugin capabilities:

<build>
    <plugins>
-       <plugin>
-           <groupId>dev.hilla</groupId>
-           <artifactId>hilla-maven-plugin</artifactId>
-       </plugin>
+       <plugin>
+           <groupId>com.vaadin</groupId>
+           <artifactId>vaadin-maven-plugin</artifactId>
+       </plugin>
    </plugins>
</build>
Note
Hilla Maven Plugin Occurrences
Note that the Hilla Maven plugin normally appears in more than one place in the pom.xml file. Be sure to replace all occurrences with the Vaadin Maven plugin.

Hilla React Projects

For projects specifically utilizing Hilla React, some dependencies can now be removed as they’re already included within the standard Vaadin 24.4.0 artifacts.

Remove the dev.hilla:hilla-react Dependency

With the integration of Hilla functionalities into Vaadin core artifacts, the separate dev.hilla:hilla-react dependency is no longer required and should be removed from your project’s dependency management to avoid redundancy and potential conflicts.

<dependencies>
    <!-- other dependencies -->
-   <dependency>
-       <groupId>dev.hilla</groupId>
-       <artifactId>hilla-react</artifactId>
-   </dependency>
    <!-- other dependencies -->
</dependencies>

Confirm that all functionalities are operational post update. Vaadin should natively support all previously Hilla-specific features.

Java Sources Changes

Update Java source files to reflect the new package names. Replace all occurrences of dev.hilla to com.vaadin.hilla, for example, in imports:

- import dev.hilla.BrowserCallable;
- import dev.hilla.Nullable;
- import dev.hilla.crud.CrudRepositoryService;
+ import com.vaadin.hilla.BrowserCallable;
+ import com.vaadin.hilla.Nullable;
+ import com.vaadin.hilla.crud.CrudRepositoryService;

Frontend Source Changes

When upgrading to Vaadin 24.4.0, it’s crucial to update import paths in your TypeScript and TSX files to align with the new package names provided by Vaadin.

The general rule is to replace all occurrences of @hilla/ with @vaadin/hilla-, and there is only two exceptions to this rule which are about @hilla/form which should be replaced with @vaadin/hilla-lit-form, and @hilla/react-components/…​ which should be replaced with '@vaadin/react-components/…​. Hence, do the replacements in the following order:

Update @hilla/form Module Imports

Change @hilla/form to @vaadin/hilla-lit-form:

- import { Binder, field } from '@hilla/form';
+ import { Binder, field } from '@vaadin/hilla-lit-form';

Update @hilla/react-components Module Imports

Change @hilla/react-components/ to @vaadin/react-components/:

- import { TextField } from "@hilla/react-components/TextField.js";
+ import { TextField } from "@vaadin/react-components/TextField.js";

General Update for Remaining @hilla/ Occurrences

Ensure that any remaining imports using the old @hilla/ namespace are updated to @vaadin/hilla-:

- import { something } from '@hilla/some-module';
+ import { something } from '@vaadin/hilla-some-module';

This includes updates to any miscellaneous modules that may not have been explicitly listed above, but are part of the Hilla suite.

Update Generated Path Imports

In case you’ve used Hilla CRUD helpers (e.g., AutoCRUD, AutoGrid, and AutoForm), there is chance that you imported generated paths from the old Hilla structure. You need to update these paths according to the new Vaadin package structure:

- import type FilterUnion from 'Frontend/generated/dev/hilla/crud/filter/FilterUnion.js';
- import type OrFilter from 'Frontend/generated/dev/hilla/crud/filter/OrFilter.js';
+ import type FilterUnion from 'Frontend/generated/com/vaadin/hilla/crud/filter/FilterUnion.js';
+ import type OrFilter from 'Frontend/generated/com/vaadin/hilla/crud/filter/OrFilter.js';

Update Authentication Code

Starting from Vaadin 24.4, the login() and logout() Hilla authentication methods automatically reload the page upon successful result from the server. Applications involving client-side handling of successful result, for example, for user info retrieval and offline storage, need to use the onSuccess() callback instead of awaiting the Promise result.

You can check if your application relies on the authentication result by searching for the ` login() and logout() in TypeScript source files. Move any code that depends on the successful result to the onSucces() callback:

- import { login as loginImpl, LoginResult, logout as logoutImpl } from '@vaadin/hilla-frontend';
+ import { login as loginImpl, LoginOptions, LoginResult, logout as logoutImpl, LogoutOptions } from '@vaadin/hilla-frontend';
import { appStore } from './stores/app-store';

// ...

/**
 * Login wrapper method that retrieves user information.
 */
export async function login(username: string, password: string, options: LoginOptions = {}): Promise<LoginResult> {
-   const result = await loginImpl(username, password);
-   if (!result.error) {
-     // Get user info from endpoint
-     await appStore.fetchUserInfo();
-   }
-   return result;
+   return await loginImpl(username, password, {
+     ...options,
+     async onSuccess() {
+       // Get user info from endpoint
+       await appStore.fetchUserInfo();
+     },
+   });
}

/**
 * Logout wrapper method that retrieves user information.
 */
export async function logout(options: LogoutOptions = {}) {
-   await logoutImpl();
-   appStore.clearUserInfo();
+   await logoutImpl({
+     ...options,
+     onSuccess() {
+       appStore.clearUserInfo();
+     },
+   });
}

By default, the server location is used as the destination after login success.

Update the Login Form

Applications that use custom navigation to proceed after the login success, such as the ones with Lit login form, need to use the navigate callback for customizing the default page reload. Update the login view in Lit applications as follows:

// ...

export class LoginView extends LitElement implements AfterEnterObserver {
  // the url to redirect to after a successful login
  private returnUrl?: string;

-  private onSuccess = (result: LoginResult) => {
-    window.location.href = result.redirectUrl || this.returnUrl || result.defaultUrl || '/';
-  };
-

// ...

  async login(event: CustomEvent): Promise<LoginResult> {
    this.error = false;
    // use the login helper method from auth.ts, which in turn uses
    // Vaadin provided login helper method to obtain the LoginResult
-    const result = await login(event.detail.username, event.detail.password);
+    const result = await login(event.detail.username, event.detail.password, {
+      navigate: (toPath: string) => {
+        // Consider absolute path to be within the application context.
+        const serverUrl = toPath.startsWith('/') ? new URL(`.${toPath}`, document.baseURI) : toPath;
+
+        // If a login redirect was initiated by the client router, this.returnUrl contains the original destination.
+        // Otherwise, use the URL provided by the server.
+        // As we do not know if the target is a resource or a Hilla view or a Flow view, we cannot just use Router.go
+        window.location.replace(this.returnUrl ?? serverUrl);
+      }
+    });
    this.error = result.error;

-    if (!result.error) {
-      this.onSuccess(result);
-    }
-
    return result;
  }
}

If the Hilla default page reload navigation is sufficient, the custom navigation in the login form could be removed. For example, applications with React login view could be updated as follows:

export default function LoginView() {
  const hasError = useSignal<boolean>(false);

-  if (state.user && url.value) {
-    const path = new URL(url.value, document.baseURI).pathname;
-    return <NavigateAndReload to={path} />;
-  }
-
  return (
    <LoginOverlay
      opened
      error={hasError.value}
      noForgotPassword
      onLogin={async ({ detail: { username, password } }) => {
-        const { defaultUrl, error, redirectUrl } = await login(username, password);
-
-        if (error) {
-          hasError.value = true;
-        } else {
-          url.value = redirectUrl ?? defaultUrl ?? '/';
-        }
+        const { error } = await login(username, password);
+        hasError.value = Boolean(error);
      }}
    />
  );
}

Move frontend Directory to src/main

In Vaadin 24.4.0, the frontend directory is moved to src/main, by default. If your project is not yet following this structure, you can move the frontend directory to src/main to align with the new Vaadin conventions. This change is recommended for consistency and compatibility with future Vaadin releases.

React File Router

Vaadin 24.4.0 comes with a File-System based router for React applications, and it’s enabled by default. This means that the Frontend/views directory will be scanned for React components and the routes are being generated based on the file-system structure of files under Frontend/views. However, if your project already has a routes.tsx file under Frontend directory, this will disable the File-System based router from being used. If you want to enable this new feature, though, read about it in File-Based Routing.

Gradle Projects: Configuration Changes

Gradle-based projects require updates to several files to accommodate the new Vaadin 24.4.0 platform. Follow these steps meticulously to update your Gradle configuration files.

Rename hillaVersion Property

Update the hillaVersion property to vaadinVersion, and set the value to the latest 24.4.x:

gradle.properties:

- hillaVersion=2.x
+ vaadinVersion=24.4.x

Don’t forget to update any references in settings.gradle and build.gradle.

Replace Hilla BOM in build.gradle

Change the Bill of Materials (BOM) from Hilla to Vaadin in your dependencyManagement closure:

dependencyManagement {
    imports {
-        implementation platform('dev.hilla:hilla-bom:${hillaVersion}')
+        implementation platform('com.vaadin:vaadin-bom:${vaadinVersion}')
    }
}

Update Hilla Core Dependency

Replace any core Hilla library dependency with the equivalent Vaadin library in your build.gradle:

dependencies {
-    implementation 'dev.hilla:hilla'
+    implementation 'com.vaadin:vaadin'
}

Update Spring Boot Starter for Hilla

Change the Hilla Spring Boot starter dependency to Vaadin’s Spring Boot starter:

dependencies {
-    implementation 'dev.hilla:hilla-spring-boot-starter'
+    implementation 'com.vaadin:vaadin-spring-boot-starter'
}

Handle React-Spring Boot Starter

Ensure that any React-specific Spring Boot starters are also updated:

dependencies {
-    implementation 'dev.hilla:hilla-react-spring-boot-starter'
+    implementation 'com.vaadin:vaadin-spring-boot-starter'
}

Replace Hilla Gradle Plugin

Switch the Gradle plugin from Hilla to Vaadin to utilize latest Vaadin’s build capabilities:

plugins {
-    id 'dev.hilla' version '2.x'
+    id 'com.vaadin' version '24.4.0'
}

Hilla React Projects

For projects that specifically utilize Hilla React, some dependencies can now be removed as they’re already included within the standard Vaadin 24.4.0 artifacts.

Remove dev.hilla:hilla-react Dependency

With the integration of Hilla functionalities into Vaadin core artifacts, the separate dev.vaadin:hilla-react dependency is no longer required and should be removed from your project’s dependency management to avoid redundancy and potential conflicts.

dependencies {
-    implementation 'dev.hilla:hilla-react'
}

Confirm that all functionalities are operational post update. Vaadin should natively support all previously Hilla-specific features.

Building for Production

For building the project for production, you should use vaadin.productionMode instead of using the old hilla.productionMode property:

./gradlew -Pvaadin.productionMode build

Final Checks

After making these changes, be sure to test thoroughly your application to verify that all dependencies are correctly linked and functioning as expected. Look for any warnings or errors in your console related to module imports or path issues, and resolve them.

Upgrading to Hilla 2.0 from Hilla 1.x

To migrate a Hilla 1.x application to Hilla 2.0, you’ll have to change several things in your application. Many of the breaking changes in Hilla 2 were introduced by the following updates of the underlying Java platform dependencies:

Jakarta EE 10 & Servlet 6

Hilla 2 is based on Servlet 6 specifications and is compatible with the Jakarta EE 10. Changing from javax. to jakarta. is required for validation and some nullability annotations in Java.

Spring Boot 3

Hilla 2 uses the latest Spring Boot 3 and Spring Framework 6 versions. This leads in turn to making breaking changes in Spring-based features compared to earlier Spring-boot 2 and Spring Framework 5 versions.

Java 17

Hilla 2 requires Java 17 or later. This is dictated by Spring framework and newer versions of application servers.

In addition to these changes in Hilla dependencies, below are notable changes in the framework itself:

Multi-Module Endpoints Parser & Generator

Hilla 2 changes the parser and generator used to produce TypeScript code for endpoints. As a result, some adjustments to code for Java endpoints and entities in Hilla applications might be required. The hillaEngine experimental feature flag was removed.

Reactive Endpoints

Released previously as an experimental feature behind the hillaPush feature flag, reactive endpoints are now enabled by default.

Vaadin Components 24

Hilla 2 complements Vaadin Flow 24 release. The Vaadin components, introduced in version 24, support styling using the ::part() CSS selector. They come with some changes that affect styling the component internals.

Preparation

Before migrating any application, a few tasks must be done. They’re described in the sub-sections here.

Set Up Node.js

Install an up-to-date version of Node.js 18 before starting a Hilla 2 migration. Be sure to have node executables in the PATH environment variable. Follow the Node.js installation instructions.

Maven Wrapper

Hilla 2 requires either a Maven wrapper script in the application, or the mvn executable in the environment, for configuring the endpoints parser and generator from the settings declared pom.xml.

If your project has mvnw and mvnw.cmd Maven wrapper scripts, Hilla 2 uses them to install and run Maven. The Maven Wrapper website offers download links and instructions for installing it in a project.

For installing Maven in your system environment, see the Installing Apache Maven documentation page.

Hilla Dependency Upgrade

Upgrade the Hilla version in the pom.xml file to the latest release like so:

<hilla.version>2.0.0</hilla.version>

You can find the latest version number in the GitHub Hilla releases list.

Jakarta EE 10 Namespaces

You can download from GitHub a couple of free tools for the package name conversion: Eclipse Transformer; and Apache Migration Tool.

When applied to a project, these tools convert as needed Java class imports, manifests, property files, and other resources to use the jakarta.* namespace. Conversion instructions can be found in each tool’s README file.

The last versions of IntelliJ IDEA offers migration refactoring tools, including a Java EE to Jakarta EE package converter.

Make sure the Jakarta specifications in your project have the proper versions. Refer to the full list of Jakarta EE 10 specifications for more information.

Below are some examples:

<dependency>
    <groupId>jakarta.servlet</groupId>
    <artifactId>jakarta.servlet-api</artifactId>
    <version>6.0.0</version>
</dependency>
<dependency>
    <groupId>jakarta.annotation</groupId>
    <artifactId>jakarta.annotation-api</artifactId>
    <version>2.1.0</version>
</dependency>
<dependency>
    <groupId>jakarta.enterprise</groupId>
    <artifactId>jakarta.enterprise.cdi-api</artifactId>
    <version>4.0.0</version>
</dependency>
<dependency>
    <groupId>jakarta.enterprise.concurrent</groupId>
    <artifactId>jakarta.enterprise.concurrent-api</artifactId>
    <version>3.0.0</version>
</dependency>

Spring Upgrade Instructions

Spring Boot 3 and Spring Framework 6 don’t fundamentally change how applications are developed. The main changes are related to Jakarta EE 10 namespaces and supported products, Java version, and the dependency upgrades and deprecations.

Spring Boot 3 and Framework 6 use new versions of third-party dependencies: Hibernate 6, Hibernate Validator 8, servlet containers — Jetty 11, Tomcat 10.1 and many others.

Spring provides the Dedicated Migration Guide for Spring-boot 3.0 and the Upgrading to Spring Framework 6.x Guide.

To browse the full list of changes, see the Spring-boot 3.0 Release Notes and the What’s New in Spring Framework 6.x page.

The following sub-sections provide a general overview of the changes needed for Spring-based Vaadin applications.

Upgrade Spring to Latest

You’ll need to upgrade Spring to the latest versions, including the starter parent dependency:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.0.2</version>
</parent>

Deprecation

Deprecated VaadinWebSecurityConfigurerAdapter was removed since Spring no longer has the WebSecurityConfigurerAdapter class. Use instead the VaadinWebSecurity base class for your security configuration. Below is an example of this:

@EnableWebSecurity
@Configuration
public class SecurityConfig extends VaadinWebSecurity {

    @Value("${my.app.auth.secret}")
    private String authSecret;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        super.configure(http);

        // Disable creating and using sessions in Spring Security
        http.sessionManagement()
                .sessionCreationPolicy(SessionCreationPolicy.STATELESS);

        // Register your login view to the view access checker mechanism
        setLoginView(http, "/login");

        // Enable stateless authentication
        setStatelessAuthentication(http,
                new SecretKeySpec(Base64.getDecoder().decode(authSecret), // (1)
                        JwsAlgorithms.HS256), // (2)
                "com.example.application" // (3)
        );
    }
}

In this example, AuthenticationManagerBuilder — used in Spring Boot 2.x — is replaced by UserDetailsService. And http.authorizeRequests().antMatchers() are replaced by http.authorizeHttpRequests().requestMatchers().

Java Version

Java 17 or later is required. Below is an example of how to use this version:

<properties>
    <java.version>17</java.version>
    <!-- OR: -->
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
</properties>

Maven Plugins

Several plugins are available for use with Maven. The ones relevant to upgrading a Hilla application to Hilla 2.0 are described here.

Hilla Maven Plugin

Starting from Vaadin 24, vaadin-maven-plugin alone doesn’t support generating Hilla endpoints. Replace it with hilla-maven-plugin to enable using Hilla endpoints:

<groupId>com.vaadin.hilla</groupId>
<artifactId>hilla-maven-plugin</artifactId>
<version>${hilla.version}</version>

You can use Maven goals of the former vaadin-maven-plugin the same way from the hilla-maven-plugin. This primarily affects hybrid applications, which have both Hilla client-side and Flow server-side views, and were created with Vaadin / Fusion 23 or earlier.

Third-Party Plugin Versions

Make sure that the versions of Maven plugins — the ones defined explicitly in your project — are compatible with Java 17. For example, nexus-staging-maven-plugin requires a minimal version 1.6.13.

SLF4J 2.0

Hilla 2, Vaadin 24 and Spring Boot 3 use SLF4J library version 2.0, which has breaking changes compared to earlier versions. See the SLF4J release notes for more information.

Changes in Hilla Endpoints

The behavior of null type annotations, such as @com.vaadin.hilla.Nonnull, has been fixed according to the Java Language Specification. In particular, this affects arrays in endpoints and entity classes:

  • @com.vaadin.hilla.Nonnull String[] is a nullable array type whose items are non-null.

  • String @com.vaadin.hilla.Nonnull [] is a non-null array type whose items are nullable.

  • @com.vaadin.hilla.Nonnull String @dev.hilla.Nonnull [] is a non-null array type whose items are non-null.

This also affects nullability in generated TypeScript code. Consider using the @NonNullApi annotation for declaring nullability on the package level.

Breaking Changes in Vaadin Components

Upgrading a Hilla application to Hilla 2 can involve several breaking changes. They’re described in the following sub-sections.

Behavior & Styling

Upgrading can lead to changes in the behavior and styling. Below is a list of these changes and what you might do to resolve problems they may cause:

  • Badges no longer shrink by default. This can be overridden with CSS [theme~="badge"] { flex-shrink:1; }.

  • Buttons no longer shrink by default. This can be overridden with CSS vaadin-button { flex-shrink:1; }.

  • Number Field’s default width now matches that of other text input components. You can restore the old default back with CSS vaadin-number-field { width:8em; }.

  • Time Picker no longer automatically adjusts values to fit min/max constraints.

  • The default top and bottom margins of the H1…​H6 HTML elements have been removed. This change can be reverted by applying the following CSS:

    h1,h2,h3,h4,h5,h6 { margin-top: 1.25em; }
h1 { margin-bottom: 0.75em; }
h2, h3, h4 { margin-bottom: 0.5em; }
h5 { margin-bottom: 0.25em; }

API of Web Components

The following changes affect the client-side APIs of Vaadin components:

  • The label on vaadin-checkbox and vaadin-radio-button must be assigned using the label property since the default slot has been removed.

  • vaadin-confirm-dialog.cancel and .reject properties were renamed to .cancelButtonVisible and .rejectButtonVisible.

  • vaadin-number-field property has-controls was renamed step-buttons-visible.

  • Deprecated @vaadin/vaadin- (e.g., @vaadin/vaadin-grid) npm packages have been removed. Use instead the new @vaadin/ (i.e., @vaadin/grid).

  • Deprecated **Element legacy class aliases (e.g., GridElement) have been removed. Use instead the plain component classes (i.e., Grid).

  • Deprecated misspelled vaadin-icons were removed: buss, funcion, megafone, palete, and trendind-down.

  • notifyResize and updateStyles methods were removed from various components as obsolete.

  • preventInvalidInput in text input fields were removed in favor of setAllowedCharPattern.

  • The read-only theme property was removed. Use instead the theme attribute.

Update Component Styling

Click and read if you have styled Vaadin components:

The internal structure of many Vaadin components has been modified to improve accessibility and enable the new, simplified styling approach in Hilla 2. These changes may affect custom CSS applied to the components.

When upgrading from Vaadin components 23 (Hilla 1) or earlier, you can refactor all CSS to the new styling approach. Another option is to stay on the old (Shadow DOM based) styling approach, and rewrite only those selectors that affect your application. Both methods can also be used in parallel, if desired.

The instructions below are based on the old approach, which is a fast way of upgrading. The new styling approach is described in the Styling section of the Vaadin documentation.

Accordion

The summary part of Accordion panels has been refactored into the separate vaadin-accordion-heading custom element, slotted into the panel component.

[part="summary"] {...}
::slotted(vaadin-accordion-heading) {...}

Parts that were inside vaadin-accordion-panel before are now in vaadin-accordion-heading:

[part="toggle"] {...}
[part="toggle"] {...}

The summary-content part was renamed to content and is now in vaadin-accordion-heading:

[part="summary-content"] {...}
[part="content"] {...}

App Layout

The background of the drawer and navbar are now defined in the parts themselves, instead of in ::before pseudo-elements:

[part="navar"]::before {
    background: ...;
}
/* and */
[part="drawer"]::before {
    background: ...;
}
[part="navbar"] {
    background: ...;
}
/* and */
[part="drawer"] {
    background: ...;
}

The navbar now has a defined min-height. This change can be reversed with the following:

[part="navbar"] {
    min-height: 0;
}

The drawer now renders a shadow when in overlay mode. It can be disabled with this:

:host([overlay]) [part="drawer"] {
    box-shadow: none;
}

Avatar Group

Individual Avatars in the Avatar Group have been moved from shadow DOM to a slot:

[part="avatar"] {...}
::slotted(vaadin-avatar) {...}

Context Menu

The context-menu item element, vaadin-context-menu-item, no longer extends the vaadin-item element, and therefore no longer inherits styling from it. Target vaadin-context-menu-item instead of vaadin-item for separate styling of the context-menu items.

CRUD

The "new item" button has been moved from the CRUD’s shadow DOM to a slot, and the new-button attribute has been removed from it:

[new-button] {...}
/* or */
vaadin-button {...}
::slotted([slot="new-button"])

The Grid inside the CRUD web component has been moved out of the CRUD’s shadow DOM to a slotted element.

Date Picker

The buttons in the Date Picker’s overlay have been moved from shadow DOM to slots:

[part="today-button"] {...}
/* and */
[part="cancel-button"] {...}
::slotted([slot="today-button"]) {...}
/* and */
::slotted([slot="cancel-button"]) {...}
/* or target both with */
::slotted(vaadin-button) {...}

The date cells in the calendar can have multiple part names to reflect their states, so the part attribute selector must use the ~= operator to match individual words:

[part="date"] {...}
[part~="date"] {...}

The state attributes for date cells have been replaced with part names:

[part="date"][disabled] {...}
[part="date"][focused] {...}
[part="date"][selected] {...}
[part="date"][today] {...}
[part~="date"][part~="disabled"] {...}
[part~="date"][part~="focused"] {...}
[part~="date"][part~="selected"] {...}
[part~="date"][part~="today"] {...}

Details

The summary part has been refactored into a separate custom element, slotted into the Details component:

[part="summary"] {...}
::slotted(vaadin-details-summary) {...}

The toggle part is now in the new vaadin-details-summary element:

[part="toggle"] {...}
[part="toggle"] {...}

The summary-content part is now in the vaadin-details-summary element, and renamed content:

[part="summary-content"] {...}
[part="content"] {...}

Login

The "Forgot password" button has been moved from shadow DOM to a slot:

#forgotPasswordButton {...}
/* or */
vaadin-button[theme~="forgot-password"] {...}
/* or */
vaadin-button {...}
::slotted([slot="forgot-password"]) {...}

The menu-bar buttons, which are also the top-level menu items, have been moved from shadow DOM to a slot:

[part="menu-bar-button"] {...}
/* or */
vaadin-menu-bar-button {...}
::slotted(vaadin-menu-bar-button) {...}

The items in the Menu Bar drop-down menus are now vaadin-menu-bar-item instead of vaadin-context-menu-item, and therefore do not inherit styling from Context Menu items.

Message Input

The text area and button have been moved from shadow DOM to slots, and replaced with regular Text Area and Button instances:

vaadin-message-input-text-area {...}
/* and */
vaadin-message-input-button {...}
::slotted(vaadin-text-area) {...}
/* and */
::slotted(vaadin-button) {...}

Message List

The message elements in the list have been moved from shadow DOM to a slot:

vaadin-message {...}
::slotted(vaadin-message) {...}

Avatars in messages have been moved to their own slots, and replaced with regular vaadin-avatar instances:

[part="avatar"] {...}
/* or */
vaadin-message-avatar {...}
::slotted(vaadin-avatar) {...}

Multi-Select Combo Box

The chip elements, as well as the overflow chip, have been moved from shadow DOM to a slot:

vaadin-multi-select-combo-box-chip {...}
[part~="chip"] {...}
[part~="overflow"] {...}
[part~="overflow"][part~="overflow-one"] {...}
::slotted(vaadin-multi-select-combo-box-chip) {...}
::slotted([slot="chip"]) {...}
::slotted([slot="overflow"]) {...}
::slotted([slot="overflow"][count="1"]) {...}

Upload

The file list has been refactored into its own vaadin-upload-file-list custom element, slotted into the Upload component:

[part="file-list"] {...}
::slotted(vaadin-upload-file-list) {...}

The upload button has been moved from shadow DOM to a slot:

[part="upload-button"] {...}
/* or*/
#uploadButton {...}
/* or */
vaadin-button {...}
::slotted(vaadin-button) {...}

The drop label and icon have been moved from shadow DOM to slots, and the icon is now a vaadin-upload-icon element:

#dropLabel {...}
/* and */
[part="drop-label-icon"] {...}
::slotted([slot="drop-label"]) {...}
/* and */
::slotted(vaadin-upload-icon) {...}