Thank you for joining the thread, @Hydrogear.

 It's my priority to help you convert your file from QuickBooks Desktop (QBDT) to QuickBooks Online (QBO). I appreciate your time and effort in reviewing your internet security settings to isolate the error code 12007. Since the error continues, you can perform additional troubleshooting steps to narrow down the result.

First, restart your computer. Then, open your file in single-user mode and reset or install the QuickBooks updates to keep your software up to date. After that, try to convert your file again. If you're getting the same result, determine whether another application or process is causing the error. If needed, you may seek help from a computer or IT expert to check the security software causing the error.

Once fixed, you're now ready to move your data right away. I'm adding this link as your reference: Moving from QuickBooks Desktop to QuickBooks Online.

When you switch data, you may notice differences in how your books appear. Find out how your data will look in QBO from here: Learn how features and data move from QuickBooks Desktop to QuickBooks Online.

Let me know if you have other questions while working with your files. I'm always here to help. Have a good one!