Hello @Chengcheng , I hope this message finds you well.

As per the documentation the "tempDir" parameter is a required one and there is no default value for it.
Databricks Synapse connector options reference: https://docs.databricks.com/en/connect/external-systems/synapse-analytics.html#databricks-synapse-co...
Could you please share some logs of any of these runs where it was possible to be executed without specifying the "tempDir" parameter?
Maybe we can find some insights from there.

Best regards,
Lucas Rocha