Why did I get "11011 - Create isolated account failed"?

Qn: Since May 15, 2021 08:00 UTC, the SAPI Create Margin Account endpoint (POST /sapi/v1/margin/isolated/create) has been deprecated and the users are suggested to directly call transfer API (POST /sapi/v1/margin/isolated/transfer). However, sometimes the following error comes out:

    "code": -11011,
     "msg": "Create isolated account failed."

This may be due to the incoming request limit at the server side. If the frequency is higher than once per second, the client side may get this error. As a temporary solution, the client side has to wait for a period of time and then retry.