The QuickBooks Unrecoverable Error usually happens when trying to open a company file or when pressing the save print or transaction buttons.
Reasons for this:
The company's file would not open because you attempted to open it
An overview of creating, closing and backing up company files
An open window in a company file needs to be closed
read here for more :
https://mamafishsaves.com/quickbooks-unrecoverable-error/