**Environment: **
APEX4.2 application migrated from 3.

Problem:
Error message: “Item ID (XXX) is not an item defined on the current page”

Solution:

• Determine what is the object with ID XXX;

select * from apex_application_page_items where item_id = XXX;

• Go to the conflicting item and change from “Display as” “Text Field” to “Text Area”
• Save

After performing this solution i could even return and change it back to “Display as” Text Field.