Thanks for the suggested fix! I bumped into the exact same NoClassDefFoundError issue while upgrading from Service Pack 19 to SP21, Jackson versions 2.13.5 and 2.16.2, respectively.  Adding the dependency worked like a charm.

Nevermind those filevault maven package plugin errors.  I'd forgotten to "Invalidate Caches" in IntelliJ.  I created a fresh clone of my Git project, changed the uber-jar dependency to 6.5.19 and added the apache commons-io maven dependency in the parent pom.xml file, and the build ended successfull...

My ui.apps package had an error: [INFO] --- filevault-package:1.1.4:validate-files (default-validate-files) @ mymodule.ui.apps.structure --- [INFO] Using generatedMetaInfRootDirectory: /path/to/project/mymodule/ui.apps.structure/target/vault-work/META-INF and metaInfRootDir: null [ERROR] Failed to e...

Yes, that's right.  I'm on Java 11, jUnit 5.

Uh, my bad, I forgot to mention those.  I did upgrade a couple of testing dependencies: the org.mockito ones (ex: mockito-core) to 5.2.0, io.wcm.testing.aem-mock.junit5 one to 5.1.2.

I also bumped into the "java.lang.NoClassDefFoundError: org/apache/commons/io/build/AbstractStreamBuilder" unit test error after upgrading to SP19.I checked in the depfinder for org.apache.commons.io, bundle was found, Maven dependency on the right column:<dependency> <artifactId>commons-io</artifa...