PA migration misc. costs error regarding period

We are migrating Project Accounting (PA) costs from a source system into Oracle. During the load of the PA interface, we encounter the following error:

“The accounting date 2026-01-01 is in an accounting period that was never opened.”

This error occurs for cost lines that are entered in the FBDI with:

• an accounting date of 2025-08-31, and
• an expenditure item date of 2026-01-01.

Currently, only the PA period Aug-25 and the GL period Aug-25 are open. Other cost lines, where the expenditure item date is prior to or equal to the accounting date, are imported successfully without any issues.