Answer. While opening or working in the QB POS application, you can receive one or more of the following errors. 1. Unexpected error happened. The error is: Value cannot be null. Parameter:s 2. Unexpected error happened, please restart Point of Sale. Exception from HRESULT: 0x88980406 3. Error: Exception has been thrown by the target of an invocation 4. Unable to open the program through the Point of Sale icon 5. Error 100 database server not found "08w01" 6. Configuration system failed to initialize 7. Error: QBPOSShell has stopped working 8. Error: 176120 invalid license key status, key