This is a new error in QBO which has been reported to our engineers, jlmconstruction2.
You'll get this error when trying to save an invoice using the Progress Invoicing feature. The suggested work around is to create an invoice from a regular estimate. To do this, you'll have to turn off Progress Invoicing first.
Click the Gear icon at the top.
Under Your Company, click Account and Settings.
Click the Sales tab on the left panel.
Click the Progress Invoicing section.
Uncheck the tick-box.
Click Save, and then Done.
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