This error is from the superfund, meaning that the rollover was initiated, passed ATO validation and was received by the superfund. The superfund has then rejected it. Unfortunately this is not very informative and doesn't provide much information regarding the rollover error reason. The expectation in Superstream for clients that receive this error is that they will reach out to the superfund and confirm directly, so this is our advice for this one.
Please ensure to provide the superfund your SMSF ABN and the conversation ID for the rollover and the superfund should be able to look up the error and advise why it failed.