ZK Developer's Reference/Upgrade Tips/Version Upgrade

Versioning

ZK products follow semantic versioning, where the three digits refer to MAJOR.MINOR.PATCH respectively. In the case where a hotfix is required, a fourth digit is introduced. Except for major (first digit) upgrades, compatibility is generally maintained, or a fall-back mechanism is available.

Upgrade References

An introductory smalltalk is published for every MAJOR and MINOR release. For example New Features of ZK 9.5. The smalltalk highlights the most important changes as well as provides upgrade tips for upgrading to that specific version. View all New Features articles.

A detailed release note containing a list of fixed issues is available for every new release, including hotfixes. For example, ZK 9.0.0 release notes. The full release history can be found here.

An “upgrade notes” section will be included at the end of a release note when needed. The “upgrade notes” section points out API changes or changes that developers will most likely need to take actions accordingly.

You can follow the same naming conventions as the examples provided above to search for the upgrade references you are looking for.

Important/breaking changes

ZK Version	Description	Reference
ZK 5.0	1. A major architectural change was made in ZK 5, affecting theming, UI creation, and client-side rendering. Upgrading from ZK 2.x or ZK 3.x to ZK 5 requires more effort. 2. Event thread is now disabled by default. You can enable it in zk.xml if you need to use it.	Release Smalltalk Upgrading to ZK 5
ZK 6.0	1. Requires JDK 5 or higher	Release Smalltalk
ZK 6.5	1. Introduced Mobile/Tablet support, EE edition will have a different style and behavior on a mobile device. You can turn it off in zk.xml if that's not desired.	Release Smalltalk
ZK 7.0	1. Re-implement the theme with new client technologies including CSS3 and LESS, and the DOM structure of components changes a lot. To upgrade a custom theme for an older version, you will need to redo the style customization based on the new theme. Please refer to Upgrade From ZK 6.5. 2. Drop IE6 & IE7 support. 3. Deprecate several legacy packages and methods relating to session and event-thread.	Custom Style Upgrade Guide Release Notes
ZK 8.0	1. A new form binding based on proxy is introduced. If you have been using MVVM org.zkoss.bind.SimpleForm, org.zkoss.bind.impl.FormImpl, and org.zkoss.bind.impl.FormExt you have to migrate it to the new proxy binding, or, upgrade to ZK 9.5 which supports the legacy simple form binding.	ZK 8 new form binding Release Notes
ZK 8.5	1. A new and default theme Iceblue is introduced. The new theme has larger margin and padding from the previous themes. If you are not ready to use the new default theme, you can switch back to the previous themes, or, use ZK 8.6’s compact theme. 2. Drop IE8 support.	Release Smalltalk Release Notes
ZK 9.0	1. ZK 9 requires JDK 8 or later versions. 2. ZK Flex uses CSS 3 Flex instead. You can disable css flex and fall back to the previous implementation if needed. 3. Packaging change: ZK Data binding 1 is moved to "zkplus-legacy"; ZK DSP Library is moved to a new module "zweb-dsp".	Release Smalltalk Release Notes
ZK 9.1	1. The underlying jQuery version has been upgraded from jQuery 1.12 to jQuery 3.5. If you have custom javascript code that relies on jQuery, you may need to update accordingly.	Release Notes
ZK 9.5	1. Optional libraries(slf4j-jdk14 and closure-compiler-unshaded) are no longer provided by default. You can plugin your preferred libraries if needed.	Release Smalltalk
ZK 9.6	1. The default desktop ID generator was replaced by a more secured one. If your tests depend on the previous generator, you can set it in system-config. 2. Deprecated the method of isEditionValid() and encodeWithZK() of org.zkoss.zk.fn.ZkFns and core.dsp.tld. 3. Since ZK 9.6, a JakartaEE-compatible package is released along with the current JavaEE-compatible package. For Jakarta EE 9 support, please use 9.6.0-jakarta version instead. 4. Since 9.6.0, the transitive dependency of jasperreports was removed in zkex. To use the jasperreport component, please add it manually.	Release Smalltalk
ZK 10.0	1. ZK 10 requires JDK 11 or later versions. 2. Deprecate old themes: Breeze, Sapphire, Silvertail, and Atlantic 3. ZK 10 works with modern browsers; IE11 and lower IE versions are no longer supported. 4. Enable InaccessibleWidgetBlockService by default in the EE version. Note that it will block Echo Event if the component is disabled or invisible. You can configure it using the library-property org.zkoss.zkmax.au.IWBS.disable. 5. ZK's corresponding features now require Java EE 7 API level, including Servlet 3.1, Bean Validation 1.1, EL 3.0, and JSP 2.3. 6. Remove all deprecated Java APIs and the legacy module "zkplus-legacy". Reference the release smalltalk and the linter tool for upgrade guidance. 7. ZK frontend is now typescript, if you have JS-based custom client-side, you may need to double-check. 8. Some add-on components are updated to support ZK 10. Please refer to Release Smalltalk.	Release Smalltalk

Check all security fixes in the tracker

Upgrade Process

Upgrading from ZK 5 (or later) to the latest version should be manageable. The steps are:

Specify the version you wish to upgrade to in your maven POM file, or, download corresponding binary files manually and put them into your project. It is important to make sure all ZK jar files are in the same version.

Then, fix any compilation errors and configure the required fallback settings by referencing the Upgrade References.

Checklist

To estimate the upgrading effort, we suggest a checklist:

1. Check Custom Components

   check if there is any ZK_Component_Development_Essentials/Creating_the_Configuration_Files/The_language-addon that might declare custom components. Since you might need to review it after the upgrade.

2. Check configuration description (zk.xml)

   Check each property in zk.xml upon ZK Configuration Reference to see if there is any change in the new version.

3. Check Custom Appearance (CSS)

   If you customize a component's appearance with CSS, you might need to review it for the new version.

4. Check Programs Using ZK JavaScript API

   If you customize a component with JavaScript, you might need to review it for the new version.

5. Check Bug Patches

   Check Bug Tracker or release note for the existing bug patch. If that bug is fixed in the new version, you can remove the patch.

6. Check for Java Compiler Error