Hi Grace,

An update on my existing post, you can use Glide Aggregate on Server side which is a Best Practice for better System Performance rather than using Glide Record on Client Side. Write an Before Insert/Update Business Rule on Catalog Task Table as below:

Condition: You can specify the Catalog Item for which you want to configure this validation by dot walking as mentioned below:

Select "Show Related Fields" option from the filter condition first and then dot walking as "Request Item-->Requested Item fields"

Post which you can select the field as "item" is "Your Item Name" as shown below:

Script:

(function executeRule(current, previous /*null when async*/) {

  var att = new GlideAggregate('sys_attachment');

  att.addAggregate('COUNT');

  att.addQuery('table_name', current.getTableName());

  att.addQuery('table_sys_id', current.sys_id);

  att.query();

  var count = 0;

  if (att.next()) {

  count = att.getAggregate('COUNT');

  if (count<1) {

  gs.addInfoMessage("Please attach Attachment");

  current.setAbortAction(true);

  }

  }

})(current, previous);

Hope this helps.Mark the answer as correct/helpful based on impact.

Regards,

Shloke