Opportunity Mass Update with Formula Set to {customer.salesrep} on Sales Rep Field Generates Unexpected Error

This is caused by the formula used on the mass update. To successfully update the Sales Rep field, perform the following steps:

1. Navigate to Lists > Mass Update > Mass Updates.

2. Expand General Updates.

3. Select Opportunity.

4. Under the Criteria tab, set the required filter.

5. Under the Mass Update Fields tab, mark the Apply checkbox for the Sales Rep field.

6. In the Formula field, enter {customer.salesrep.id}

7. Click Preview.

8. Click Perform Update.