To fix QuickBooks error code 15212, you can try the following steps:
Make sure that the shared download location for QuickBooks updates is mapped and is accessible.
Make sure that the shared download location for QuickBooks updates has sufficient disk space.
Repair the QuickBooks installation. To do this, open the QuickBooks Tool Hub and select the Install Diagnostics tool.
Disable any third-party programs that you are not using.
Update QuickBooks or QuickBooks Payroll manually. To do this, go to the QuickBooks website and download the latest updates.
Regards,
Peter