The error you're encountering with the MCS catalog creation, specifically the
Error Id: XDDS:068753FF indicates a failure related to unregistering the master image from the Mobile Device Management (MDM) system. This issue is commonly associated with the master image being improperly managed by MDM or MAM (Mobile Application Management)

Caution! Using Registry Editor incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

This issue typically occurs when the master image is improperly managed by either MDM (Mobile Device Management) or MAM (Mobile Application Management). The system attempts to unregister the master image as part of the catalog creation process, but if the image is not correctly configured or managed, this step fails and prevents catalog creation.

1. Modify Registry Settings on the master-image, which is used for catalog creation

You can resolve this issue by disabling MDM unregistration in the registry.

Follow these steps:

Path: HKEY_LOCAL_MACHINE\Software\Citrix\MachineIdentityServiceAgent

Key: DisableMDMUnregistration

Type: REG_DWORD

Value: 1

Setting this registry key will prevent the MDM unregistration step during image preparation, which is often the root cause of the error.

Note:  Before making any changes to the registry, ensure you take a complete backup. Incorrect modifications can lead to system instability.

2. Build New Catalogs Using Manual Deletion Process

If modifying the registry does not fully resolve the issue, you can also create new catalogs by manually deleting previous catalog references. This ensures that the new catalog creation process starts with a clean state, avoiding conflicts caused by previous failed attempts.

MCS catalog creation fails with unknown error on Windows 11 24H2 VDA in CVAD 2507 LTSR CU1.

Note:  Before making any changes to the registry, ensure you take a complete backup. Incorrect modifications can lead to system instability.