In Sales Engagement, Tasks automatically created by a Cadence (Task records with Subtype "Cadence") cannot be manually edited.
Attempting to edit these Tasks results in the error:
Can’t edit tasks created by cadences. These tasks are auto-updated as prospects advance through the cadence
Tasks created automatically by a Sales Engagement Cadence have a Subtype of Cadence and are managed entirely by the Cadence engine. Salesforce updates these tasks automatically as the prospect advances through each step of the Cadence, which is why manual editing is disabled. To remove a Cadence task, wait until the associated Cadence step is completed, then delete the task record if needed
Salesforce Help: Cadence Considerations for Sales Engagement
Customer Idea: Allow manual editing of Cadence-created Tasks (IdeaExchange — feature request, not currently available)
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