When creating a Case or Lead record in Salesforce via the API or Apex, you may encounter the error: INSUFFICIENT_ACCESS_ON_CROSS_REFERENCE_ENTITY. This error typically occurs when the running user does not have access to the email template folder referenced by a Case or Lead Assignment Rule.
Assignment Rules in Salesforce automatically assign newly created records to specific users or queues based on predefined criteria. When these rules are configured to send an email notification, they reference an email template stored in a folder. If the running user does not have permission to access that folder, Salesforce raises this error and the record creation fails.
To resolve this error, grant the required access level to the user for the folder in which the email template is stored.
View an Edit Email templates in Salesforce Classic
Manage Public and Private Email Templates in Lightning Experience
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