I'm trying to Upsert Tasks to their Accounts using an ExternalID field but the 2nd step (Step 2b) doesn't appear with a Task Upsert.

Does Task not support External IDs for Account-association?

Also, to add to the confusion, You can't actually create "Task Fields", but instead, we can Create "Activity Fields" which is used on Task Page Layouts.

So the actual External ID field is on the Activity object. But you can't select Activity in Dataloader, instead, you use Task or Events.

  • 1
    You would need to replace Account external Ids with actual Salesforce Ids that are present in your system in this case. Approach would be to export target account with ext id field (hopefully populated), and then using VLookup (excel) to populate WhatId in your source csv file.
    – Mahmood
    Commented Mar 17, 2020 at 20:01
  • @steve Realfire allows you to parent id map even if the field is polymorphic (as in this case or other fields like whatid etc). You can specify a business value and specify which object it needs to load it from and it will lookup ids and upsert the records. [Disclaimer, I'm part of the team that builds Realfire]
    – metasync
    Commented Apr 17, 2020 at 2:19

1 Answer 1


If you are trying to associate tasks with Accounts using the external Id. The parentId field on task is polymorphic and can relate to different objects. The linking to Account won't work because of that.

Here is an Idea on IdeaExchange to have this implemented but it hasn't seen much traction as of now from Salesforce.

An easier way would be to query the accounts and use VLookUp to associate tasks or activities to accounts and then do a data load.

  • That sucks... Thanks man
    – Steve
    Commented Mar 17, 2020 at 20:03

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