I get a file not found when I try to save my file. Why?

Turn off Controlled Folder Access:

• Select Start  > Settings .
• Choose Update & security  > Windows Defender.
• Select Open Windows Defender Security Center.
• Select Virus & threat protection, and then choose Virus & threat protection settings.
• Under Controlled folder access, turn it off.

Another and more preferable option is to add TurboTax to the controlled folder access list.

Basically, turbotax.exe needs to be added to the "allowed apps" controlled folder access list.

To do this manually in Windows 10:

 - Select Start - Settings - Update & Security
 - On the right pane select Windows Security, then click the Open Windows Security button at the top.
 - Select Virus & Threat Protection.
 - Scroll down and click Manage Settings.
 - Scroll down to Controlled Folder Access and under that click Manage Controlled Folder Access.
 - By default, Controlled Folder Access should be on. Under that click Allow an App through Controlled Folder Access.
 - Click Add an Allowed App.
 - You're doing this because TurboTax is blocked already. So select Recently Blocked Apps and TurboTax will be listed there. Select it, and press on through the rest of the screens to complete the process of adding TurboTax to the list of allowed apps.

You do not have to turn off Controlled Folder Access.  You can simply add TurboTax to the allowed list of apps in the Controlled Folder Access settings and it will work. If you have Windows 10 version 1809, under Virus & Threat Protection, click on Allow an app through Controlled folder access.  Click + Add an allowed app> Recently blocked apps and you should see TurboTax.exe in the list of blocked apps. Click the + sign to add it to the allowed apps.  I did this and saving works fine with no problems while still leaving ransomware protection turned on to block access from other unauthorized programs.

Thanks Leon. Added the steps for that option above.

I have Windows 10 Home Version 1803. Recently blocked apps are not an option. I had to navigate to Program Files(x86)\TurboTax\Premier 2018\32 bit\TurboTax (application) and then add.

You just need to update to version 1809 is all, and then you'll have the ability to do it my way. Luckily, you were able to figure it out for your outdated version.

Jake54 - thanks for your post since I did not think about excluding the application - although I am updated and have the win pro version, I use Bitdefender, not Defender so the Defender options did not do any good. I initially excluded in Bitdefender just the folder where I keep my turbotax files, but that didn't suffice - seeing your post it dawned on me it was the turbotax application doing the saving so that is what needs to be excluded - all works now - so thanks Jake!