Error in approval using Position Hierarchy

Summary

Error in approval using Position Hierarchy

Content

I am trying to set approval rule using position hierarchy. But when approval PO, it throw an error: "Error occurred while displaying History tree table. Error in evaluating routing slip. Check the underlying exception and correct the error in the routing slip.".

I already configured Position Tree, assign each user to each position in the position tree.

I also looked for the error, there is a note: Position Hierarchy Is Not Working For Purchase Requisition (Doc ID 2225794.1). The document said that: "Set the Effective start date to a past date, before last server restart". But I don't know what the last server restart date is.