Issue Adding Plan (Preview) in Fabric - “Error while initialization database connection”

Hi abelkar, 
Thank you for reaching out to the Microsoft Fabrc Community Forum.

Based on your setup (F64 capacity, correct security group, and the feature enabled in your region), this does not look like a permissions or licensing issue. The error “Error while initialization database connection” typically occurs when Fabric cannot complete the backend database connection required while creating the Plan (Preview) item. As per Microsoft guidance, Plan creation depends on initializing a database connection, and if that step fails, this error can occur:
1. https://learn.microsoft.com/en-us/fabric/iq/plan/planning-how-to-create-database-connection 

In preview features, this is usually related to backend provisioning delays or partial rollout, even if the option is visible in the UI. You can try validating the workspace is on F64 capacity, creating the Plan in a new workspace, or retrying after some time. Additionally, ensure there are no network restrictions, private endpoints, or tenant-level policies blocking required Fabric services, as these can also impact connection initialization.

Also refer to:
2. https://learn.microsoft.com/en-us/fabric/data-factory/connector-troubleshoot-fabric-sql 
3. https://learn.microsoft.com/en-us/power-apps/maker/data-platform/fabric-troubleshoot 

Hope that clarifies. Let us know if you have any doubts regarding this. We will be happy to help.

Thank you for using the Microsoft Fabric Community Forum.