Migration SDK Error — TableauInstanceTypeNotSupportedException: The operation is not supported on Unknown

[Prashant-IH]

We are encountering a persistent issue using the Tableau Migration SDK (Python wrapper over .NET SDK v5.3.1) when attempting a Server-to-Cloud content migration.
{
"ClassName": "Tableau.Migration.TableauInstanceTypeNotSupportedException",
"Exception": {
"Message": "The operation is not supported on Unknown.",
"UnsupportedInstanceType": "Unknown"
}
}

We are correctly initializing the plan builder with the following parameters:

plan_builder = plan_builder
.from_source_tableau_server(
server_url = "",
site_content_url = "",
access_token_name = "",
access_token = "<valid_token>"
)
.to_destination_tableau_cloud(
pod_url = "",
site_content_url = "",
access_token_name = "",
access_token = "<valid_token>"
)
.for_server_to_cloud()

The SDK fails to auto-detect the instance type of the source Tableau Server (Unknown is returned instead of Server).

We confirmed that our Tableau Server does respond to /api/3.25/serverinfo, returning hosted: false, which indicates it's a Server instance.

Access tokens and site URLs are correct — other endpoints are accessible.

This issue did not occur in SDK version 5.2.0.

We suspect the migration SDK is failing to parse or identify the instance type from the /serverinfo response or is not calling it correctly.

This issue occurs just before "Tableau.Migration.Content.Schedules.Server.IServerExtractRefreshTask" although the users, Groups,
DataSource and Workbook Migrated Successfully.

Please advise on the following:

Is there a known regression in SDK v5.3.1 related to TableauInstanceType.Unknown?

How can we solve this Issue asap?

[dngtableau]

Hi Prashant,

Thank you for your inquiry. Can you provide the migration logs and manifests from the failing migration? Based on the current information I'm unable to investigate the root cause of the issue. In the meantime as a workaround are you able to downgrade to 5.2.0?

Thanks.