The "QuickBooks Unrecoverable Error" happens when the program has serious problems, which are frequently brought on by corrupted data, unfinished updates, or system crashes. Workflows may be disrupted by this problem, which usually shows an error code. In order to fix problems and restore seamless operation, troubleshooting methods including fixing the installation, updating QuickBooks, or restoring a backup are required. If you would like to speak with a QuickBooks support specialist immediately, please contact us at +1.833.802.0002.
https://quickbooks-error-support.odoo.com/blog/blog-2/quickbooks-unrecoverable-error-9