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Troubleshooting output generation failures in AEM Guides after DITA-OT/Saxon upgrade

Last update: August 27, 2026

In Adobe Experience Manager (AEM) Guides, output generation jobs fail intermittently after upgrading a custom DITA-OT/Saxon package, even when the source content and configuration remain unchanged. The issue includes duplicate document-URI errors and initialization failures related to missing dependencies during output generation. To fix this issue, update the DITA-OT configuration, verify required dependencies, and reload the affected DITA profile configuration.

Description description

Environment

Adobe Experience Manager Guides with a custom DITA-OT/Saxon package (all versions; issue observed after DITA-OT/Saxon upgrade)

Issue/Symptoms

  • Output generation jobs fail intermittently.
  • Initialization failure: Error loading org/slf4j/Logger during DITA-OT startup.
  • Transformation failure: Duplicate document-URI error referencing subjectScheme.ditamap.
  • Successful and failed runs occur with the same configuration and content.

Cause

  • The duplicate document-URI error is likely due to stricter validation or URI handling introduced by the upgraded DITA-OT/Saxon version, causing the same subject-scheme document to be resolved more than once.
  • The org/slf4j/Logger initialization failure points to a missing dependency, incomplete package, or classpath misconfiguration in the updated custom DITA-OT package.
  • Deployments via code may not trigger the necessary in-memory profile synchronization, requiring a manual save to reload the configuration.

Resolution resolution

Follow the steps below to resolve the issue:

  1. Add subjectScheme.ditamap to the duplicate-map scan exclusion list in your DITA-OT/Saxon configuration. After applying the change, validate that output generation works as expected and review the results for any unintended side effects.
  2. Verify that all required SLF4J dependencies and JAR files are present in the custom DITA-OT package deployed to AEM.
  3. Ensure that the DITA-OT ZIP package is complete and includes all required libraries.
  4. Review the classpath configuration in the DITA profile and confirm that it contains all required dependencies for the updated toolkit.
  5. If the DITA profile was deployed through code or a package, manually reload the configuration by opening the affected DITA profile in the AEM Guides UI, removing the currently assigned path values, saving the profile, reassigning the same path values, and saving the profile again. Wait approximately 10 to 15 minutes for the configuration to propagate.
  6. Retry output generation.
  7. Compare the local DITA-OT package with the package deployed to AEM and confirm that both packages are consistent.
  8. If the issue persists, collect and review error logs from failed generation jobs for additional troubleshooting.
  9. Run an output generation job and verify that the errors no longer occur and that output generates successfully.
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