I would like to define a workflow whose rule criteria is that a Lookup field changed, but ISCHANGED and PRIORVALUE generate syntax errors. Both generate the message

Error: Function (PRIORVALUE|ISCHANGED) may not be used in this type of formula

Is it possible for a workflow to determine when a Lookup has changed or is the Trigger territory?

1 Answer 1


Priorvalue and ischanged are allowed if the workflow type is "any time a record is created or edited". If you change to that it should be allowed.

From Salesforce help:

This function is available only in:

  • Assignment rules
  • Validation rules
  • Field updates
  • Workflow rules if the evaluation criteria is set to Evaluate the rule when a record is: created, and every time it’s edited.
  • I did not see that in the documentation; thank you!
    – Mike Chale
    Oct 17, 2012 at 16:52

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