Issue Summary

When attempting to run user (email) assessment, this part of the process fails due to an issue in the underlying jackson library used to scan for invalid user accounts. This result halts migration assessment as the users have no way of progression.

Steps to Reproduce

1. Prepare Confluence version between 8.8.0 and 8.9.5.
   1. Note

      This confluence versions use the embedded crowd version 5.2.1. And this issue does not occur in 9.0.1 or higher, which uses crowd 6.0.0

1. Install CCMA version 3.11.6 or higher.
2. Create a users that are either duplicate or have invalid email domains.
3. Open CCMA and go to Assistant Home
4. Click 'Assess and prepare your users' menu.
5. Click cloud instance and go to 2nd page and click 'Begin Assess'
6. The CCMA fails to assess users with the following error:

   1. We’re unable to assess your users right now. Try running the assessment again or come back later.

7. Assess again to see below error.

Expected Results

The invalid/duplicate email assessment is successful and the user can continue to the next page ('Choose method')

Actual Results

The CCMA fails to assess users with the following error:

We’re unable to assess your users right now. Try running the assessment again or come back later.

In the Catalina.out log, below error is printed.

02-Jun-2025 13:12:28.552 WARN ....
Exception in thread "UDC user base scan" java.lang.LinkageError: loader constraint violation: loader org.apache.felix.framework.BundleWiringImpl$BundleClassLoader @29d1bc4e wants to load abstract class com.fasterxml.jackson.databind.introspect.Annotated. A different abstract class with the same name was previously loaded by org.apache.catalina.loader.ParallelWebappClassLoader @4a02b053. (com.fasterxml.jackson.databind.introspect.Annotated is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @4a02b053, parent loader java.net.URLClassLoader @2b2948e2)
	at java.base/java.lang.ClassLoader.defineClass1(Native Method)
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1022)

Workaround

For assessing users, manually query and fix for the confluence backend database. Follow the SQL instructions in:

• Invalid email addresses in the migration user assessment check
• Duplicate email addresses in the migration user assessment check

Alternatively, Confluence DC 9.0+ does not suffer from this issue, however, upgrading confluence to 9.x (preferrably 9.2 LTS) comes with its own warning. Please refer to Confluence 9.0 upgrade notes for full breaking changes.