Hello there, @Simeon.
Allow me to join this thread and add some additional information regarding the issue that you're encountering.
First off, I want to confirm if you want to update your existing transactions or close your books. If you want to close your books, that's when you'll be given the option to enter a closing date. However, if you mean to update your existing transactions, you only have the option to choose a start date which is showing based on your screenshot.
To fix this, I recommend adjusting the start date range as stated in the screenshot.
If you're still getting the same error message even after changing the start date range, I suggest contacting our Customer Support Team. You can follow the steps on how to contact them given above by @JaeAnnC.
I'm also adding this reference for tips and dates to remember in preparation for the coming year-end: Year-end guide for QuickBooks Online.
Don't hesitate to leave a comment below if need any additional assistance in managing your books and transactions in QuickBooks Online. Have a great day!
