Placement of Lookup Post Function on Creating Issue

Background

Depending on where your lookup post function is placed in "create" workflow transition, users will receive the different error messages on issue creation when their lookup field is empty.

Before "Create the issue originally"
After  "Create the issue originally"

Recommendation

To display our customised error message for the value of the field used for the lookup, we would recommend users to place their lookup post function before "Create the issue originally".