locked fiscal period

Just got a new lap top - had data transferred over - everything was fine entering up until the end of Aug.  Now in Sept when I go to post an invoice I get an invalid entry message - the date entered is within a locked fiscal period. Please enter a valid date to proceed.  Our fiscal year end is March 31, 2022.  Been using BV for 27 years - never had an issue like this.  How do I fix?