After configuring an asset publisher display template and applying fix pack 20, a free marker error appears when trying to configure the asset publisher

Issue

After creating an Asset Publisher Display Template and installing fix pack 20 to my Service Pack 5 (SP%), I cannot configure the Asset Publisher. I received an Internal Server Error in the UI and a Free Marker Template error in the logs.

Reproduction Steps:

1. Set up DXP 7.2 SP5 with fix pack 14

2. Go to Site Builder -->Widget Templates --> and add an Asset Publisher Template

3. Go to Content & Data --> Web Content and create basic web content.

4. On the Home page place an Asset Publisher and configure its Display with the Asset Publisher Display Template.

5. Shut down the instance.

6. Install Fix Pack 20

7. Start the instance and try to configure the Asset Publisher.

Actual Result: An Internal Server error appears in the UI and a Free Mareker Template error in the log like this:

Error executing FreeMarker template

FreeMarker template error:

Java method "com.liferay.portal.layoutconfiguration.util.velocity.TemplateProcessor.processMax()" threw an exception when invoked on com.liferay.portal.layoutconfiguration.util.velocity.TemplateProcessor object "com.liferay.portal.layoutconfiguration.util.velocity.TemplateProcessor@18992655"; see cause exception in the Java stack trace.
----
FTL stack trace ("~" means nesting-related):

 - Failed at: ${processor.processMax()}  [in template "classic_WAR_classictheme_STANDARD_pop_up" at line 4, column 25]

Expected Result: The Asset Publisher can be configured without any issues.

Environment

Liferay DXP 7.2

Resolution

The issue is caused by the fix pack 20 installation to Service Pack 5 (SP5 or any SP lower than SP8). According to the fix pack 20 installation information: https://customer.liferay.com/downloads?p_p_id=com_liferay_osb_customer_downloads_display_web_DownloadsDisplayPortlet&_com_liferay_osb_customer_downloads_display_web_DownloadsDisplayPortlet_productAssetCategoryId=118681159&_com_liferay_osb_customer_downloads_display_web_DownloadsDisplayPortlet_fileTypeAssetCategoryId=118681166

You should remove the following Liferay Data Engine lpkgs in osgi/marketplace before installing fp20:

LIFERAY_HOME/osgi/marketplace/Liferay Data Engine - API.lpkg

LIFERAY_HOME/osgi/marketplace/Liferay Data Engine - SPI.lpkg

LIFERAY_HOME/osgi/marketplace/Liferay Data Engine - Impl.lpkg

This is the documentation related to it: https://help.liferay.com/hc/en-us/articles/9562681522829-Startup-errors-after-installing-DXP-7-2-Fix-Pack-20