Good to see you in the Community forum, @NNC. Let me help share information about the error you've encountered when installing the QuickBooks Desktop Enterprise 2018.
Since QuickBooks Desktop 2018 is not yet supported, you must upgrade to the most recent version to avoid receiving the pop-up error warning while opening the company file. Issues like this are usually occurring due to software incompatibility, and discontinued versions won't receive the latest critical security patches and updates.
To ensure you'll enjoy all the benefits and services that QuickBooks offers, you might want to upgrade to the newest version. With QBDT's 3-year life cycle of its company data, upgrading it will take time to avoid possible data issues.
If you want to upgrade your QBDT, you'll need to back up your company file first on your QuickBooks Desktop (QBDT) 2018 version. Once done, you'll have to restore it to your QBDT 2021 to upgrade the file. Note that you'll no longer be able to open the file in QBDT 2018 once the upgrade is complete.
Here's how:
- Open your QuickBooks Desktop 2018 and go to the File menu.
- Hover over Back up Company and select Create Local Backup.
- Choose Local Backup and then Next.
- Click Browse and choose where you want to save your backup company file.
- Click OK.
- In the Create Backup window, specify whether to back up automatically, and select Options to set options for automatic backups.
- Select New to set a backup schedule in the Schedule Backups dialog.
- Click Finish.
For more info about the process, see this article: Back up your QuickBooks Desktop company file.
Then, you're now ready to upgrade the file to QBDT 2021. To guide you through the process, please check out this link: Upgrade your company files after you switch to a new version of QuickBooks Desktop.
If you're looking for information or articles to bookmark or keep for later use, you can always go to the QuickBooks Help articles page. You can search manually by entering a term in the search area, or you can browse the categories provided.
If you require additional assistance with upgrading your file, please leave a comment below. I'm only a post away and would be happy to assist you in any way I can. Take good care.
