Error 0x801F0005 when using source folder option

That error comes from a file system filter on C: (antivirus, backup, security software) refusing the operation, not from RAM FS itself. We can't reproduce it on a stock Windows system: your exact Outlook Logging path and a folder in the root of C: both mount fine with Defender running.

If you'd like us to look into it, please run this in an administrator Command Prompt and post the output:

fltmc instances

Otherwise, a simpler way is to redirect TEMP and TMP to a RAM FS volume in Tools → Set Windows Temporary Folder. Outlook Logging lives in your Temp folder, so it moves along with every other application's temporary files, not just Outlook's. Add Temp to the volume's Create Folders list so it exists from boot, then sign out and back in.

Thanks for the fltmc output, it was exactly what we needed. It pointed straight at the OneDrive cloud files filter (CldFlt) on C:, so we could reproduce the error quickly and trace it to how RAM FS renamed the source folder, which that filter refuses. It affects any PC with OneDrive, so your report helped a lot of people.

The fix is in this snapshot build. Please install it over, reboot and let me know how it goes.

Alternatively, there are two other options:

1. Move your whole TEMP/TMP to RAM FS except for those poorly written apps. Set TEMP and TMP to RAM FS in Tools → Set Windows Temporary Folder, and start each of those apps from a batch file that points it back to the original folder:

@echo off
set TEMP=%LOCALAPPDATA%\Temp
set TMP=%LOCALAPPDATA%\Temp
start "" "C:\Path\To\Program.exe"

2. Link just the Outlook folder to RAM FS. Close Outlook, delete the Outlook Logging folder, and run this in a normal Command Prompt:

mklink /J "%LOCALAPPDATA%\Temp\Outlook Logging" "T:\Outlook Logging"

Then add Outlook Logging to T:'s Create Folders list so it exists after every restart.