S4D will automatically send a detailed error email messages message when the Save To Dynamics Submit Action experiences a fatal error, provided that the email settings are correctly configured.
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Emails include:
Configuration. : The Submit Action properties defined on the form.
Mapped form values. : The fields mapped to the Dynamics 365 entity including values submitted.
Log messages. : Logs from all levels regardless of the current Sitecore logging settings , that occurred during the Submit Action execution . Limited (limited to the the last 100 lines).