Unknown error - Change Workspace Name

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

Renaming a Power BI workspace is a supported operation both in the Service UI and via the REST API, provided you are a workspace Admin. When the rename fails in both places and returns an HTTP 500 with a generic UnknownError, that is a strong indicator of a service-side failure, not a permissions issue or a problem with how the request is made. A generic 500 error means the request passed authentication and basic validation but failed during internal processing in the Power BI backend. If this were due to permissions, naming rules, refresh locks or unsupported scenarios, Power BI would return a specific and descriptive error instead of UnknownError.

Because the same error occurs through the REST API, browser state and client-side factors are effectively ruled out. At that point, the issue is typically caused by a transient service issue, a backend bug related to the workspace’s internal state, or a tenant/capacity-specific problem. If the issue persists after waiting and retrying, the correct next step is to raise a Microsoft Support ticket and provide the workspace ID and timestamp. This is one of those cases where the problem cannot be reliably fixed from the user side.

Below is the link to help create Microsoft Support ticket:
How to create a Fabric and Power BI Support ticket - Power BI | Microsoft Learn