In Jira issue view, when clicking Push, an error message "This connection is not allowed to modify Salesforce data!" appears on the screen.
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The Allow Modification connection is configured as read-only, restricting the user from performing a manual push to Salesforce.
Go to Apps > Salesforce > Connections.
Click Configure on the existing connection.
Scroll to the "Connection Settings" section.
Enable the Allow Modification toggle.