source_holder_changed
Source holder changed. The HTTP status depends on the call.
The domain's holder at the registry changed after the holder change was approved. The change was stopped and nothing was changed at the registry.
What to do
Read the current holder with GET /api/v2/domains/{id}/contacts. Then start the holder change again.
Branch on code, not on title or detail. When you contact support about it, include the requestId. More in Errors and retries.