Experience Builder apps fails to load in Portal for ArcGIS and display a 404 Not Found error for /experiencebuilder/cdn/365/jimu-core/init.js

Description

In Portal for ArcGIS, Experience Builder applications fail to load and remain stuck on the initial loading screen. In the browser’s developer tools, the Network tab shows a 404 Not Found error for the following resource:

https://<portaldomain.com>/webadaptor/apps/experiencebuilder/cdn/365/jimu-core/init.js

Cause

This occurs when the Experience Builder directory in the Portal for ArcGIS installation folder (C:\Program Files\ArcGIS\Portal) is incomplete or corrupted. Specifically, the affected path for Experience Builder is C:\Program Files\ArcGIS\Portal\apps\experiencebuilder\cdn\365. When required core files are missing from this directory, Portal for ArcGIS is unable to load the Experience Builder framework, resulting in applications remaining stuck on the loading screen and returning a 404 Not Found error. As a result, Experience Builder and other Portal-based applications fail to load until the missing files are restored.

Solution or Workaround

To resolve this issue, restore the missing or corrupted Experience Builder files using one of the following methods.

Repair the Portal for ArcGIS installation

1. Repair the Portal for ArcGIS installation. Refer to Microsoft Support: Repair apps and programs in Windows for instructions. This process automatically restores missing or corrupted files within the Portal installation directory without affecting the current configuration.
2. After completing the repair, restart the Portal for ArcGIS service and verify that Experience Builder and other applications load correctly.

Restore the directory from a backup or another Portal for ArcGIS installation

1. If you have a backup of the Experience Builder directory or access to another Portal for ArcGIS installation at the same version, copy the missing folders from: C:\Program Files\ArcGIS\Portal\apps\experiencebuilder\cdn\365.
2. Paste the files into the same path on the affected machine. Ensure all required core files are present.
3. If multiple applications are affected or the corruption is more extensive, copy the entire Portal installation directory (C:\Program Files\ArcGIS\Portal) from a backup or from another machine running the same version.
4. Restart the Portal for ArcGIS service and verify that all applications load without errors.