Overview:
The user is not able to open a Change Control on a document classified under a specific Document Type.
Root Cause:
The affected Document Type is not configured correctly.
Solution:
The solution is to ensure that the Create Draft requires Change Control option is selected in the configuration for the affected Document Type. This setting is enabled on all Sub-types and Classifications that are under the Document Type. This setting does not automatically propagate to child types when it is enabled at the Document Type level.

Related Documentation:
- Vault Change Control Documentation: About Single-Document Change Control (QualityDocs)
- Vault Admin Documentation: Configuring Document Types
Thank you