Hi MSWF
Thanks for clarifying, this can sometimes happen if there are Purchase orders recorded with "Professional" or "Miscellaneous" layouts.
A quick way to determine which purchase orders need to be change is to use the import/export assistant, to export the Purchases, filtering by order, and by each of the layout types causing the issue. Select the minimal export fields needed to determine the purchase orders.
Purchase No.
Co./Last Name
You can then open this list in notepad or excel for quick reference.
If the error persists in the selected date range with only service or item layouts, remove all invalid characters from the reference number of each transaction.
If that does not resolve the issue, attach the diagnostic log after attempting to generate the report so we can investigate further.