Hey @nameisnani 

Use:

• Data Policy → Make Work Notes mandatory
• Before Business Rule → Change State to In Progress

This is more reliable than a UI Policy because Data Policies and Business Rules are enforced across all channels, including Service Operations Workspace.

Step 1: Create a Data Policy

Navigate to:

System Policy → Data Policies

Click New

Configuration

Conditions

State = On Hold

Create a Data Policy Action:

Note: If the requirement is only during reassignment, the Business Rule below will enforce the final validation server-side.

Step 2: Create a Before Update Business Rule

Navigate to:

System Definition → Business Rules

Click New

Configuration

Leave Condition blank.

Business Rule Script

(function executeRule(current, previous) {
    var reassigned =
        current.assignment_group.changes() ||
        current.assigned_to.changes();

    if (previous.state == 3 &&
        current.state == 3 &&
        reassigned) {
        // Validate Work Notes
        if (gs.nil(current.work_notes.toString())) {
           gs.addErrorMessage(
                'Work Notes are mandatory when reassigning an On Hold Incident.'
            );
            current.setAbortAction(true);
            return;
        }
        // Move State to In Progress
        current.state = 2;

    }

})(current, previous);

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If this response helps, please mark it as Accept as Solution and Helpful.

Doing so helps others in the community and encourages me to keep contributing.

Regards

Vaishali Singh

Servicenow Developer
Linkedin - https://www.linkedin.com/in/vaishali-singh-2273361bb