The warning Cannot associate projects outside the main project’s period appears when trying to link a subproject (child project) to a main project (parent project), but the child’s period is outside the parent’s period.
The project date is a planned date, in this case, the parent project’s date must be the same as the child projects’ date, following the same logic as parent actions and child actions, that is, the parent project’s start date must be the earliest date among the child projects and the parent project’s end date must be the latest date among the child projects.
Example:
Parent Project ———— 01/01/2023 to 31/12/2024 (duration: 2 years)
Child Project1 ——- 01/01/2023 to 31/12/2023 (duration: 1 year)
Child Project2 ——- 01/01/2024 to 31/12/2024 (duration: 1 year)
Attention: if the children have an end date provided, the parent must also have one.