Here, While you are create voucher for your previous month by default system should not allow generate, system show the warning/Error message (Fig-1), this case, If you have accounts access, you can allow to generate previous month/period vouchers, Please find the below steps for generate Increase grace period.
1. Login with Fresa Application. Goto Accounts->Accounts – Settings –> JV period master, (Fig-2)
2. As per above image, trying to generate voucher previous month and required 30 days from the current date, So kindly open required period master(Fig-3),
3. Edit the period master and change the grace period as per your date range requirement , as per above image requirement required 30 days and mention GL days as 30 (Fig-4)
(This is very sensitive change if you change the period date range, It will affect your Account, once voucher generated for that financial year, So kindly change AR, AP and GL Grace period only).