For the Modern UX the error is: Fiscal time periods do not exist, or are inactive for the investment's scheduled dates. Either change the investment dates, or create and activate the missing time periods this is when clicking "Populate From Allocations" on "Financials" tab for a project in modern UX the following error appears
For the New UI:
REVMGR-20971: Fiscal time periods do not exist, or are inactive for the investment's scheduled dates. Either change the investment dates, or create and activate the missing time periods.
For the Classic UI:
REVMGR-20971: Time periods do not exist for the duration of the project
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For the classic UI, this message is generated when creating a new cost plan, populating data from the Investment Team or from Task Assignments. This message indicates that there are missing Fiscal Time periods for the entire duration of the project. There might be an existing period for the Start Period or the Finish Period, but not for all periods in the date range. You need to look at the Project Start and Project End dates and ensure that there are defined, active fiscal time periods of the 'Period Type' specified, that encompass the entire project date range.
If the Project dates can be modified, try changing the dates to fit into existing, active fiscal time periods. If not, then add more fiscal time periods to allow the cost plan to be created so it covers the project dates. Alternatively, if you do not want to activate new fiscal time periods, change the 'Period Type' selected on the Cost Plan Create page to use a different set of fiscal periods where there are active periods to cover the dates of the project.
Steps to check Fiscal Time Periods configuration: