javax.jcr.NamespaceException: Unknown namespace prefix error in AEM

This article offers a solution to the error "javax.jcr.NamespaceException: Unknown namespace prefix" in AEM.

Description description

Adobe Experience Manager

If the error below appear in the logs:

javax.jcr.NamespaceException: Unknown namespace prefix: [ namespacename]
Could not Build Package "Unknown namespace prefix: [ namespacename]


This error usually shows up in environments where partial data migration was done using the crx2oak tool.
The crx2oak tool doesn’t support migrating namespaces with the data.

Resolution resolution

To resolve this issue, follow these steps:

  1. Register the missing namespaces via the CRX Explorer:

  2. Go to http://hostname:port/crx/explorer/index.jsp and log in as admin user.

  3. Click  Node Type Administration  in the CRX Explorer.

  4. In the  Node Type Administration  window, click  Namespaces, which is at far right of the toolbar.


  5. At the bottom of the Namespaces window, click  New.

  6. Enter the URI and the Namespace mapping, then click  OK.

  7. Enter the prefix of the Namespace mapping, then click  OK.