I was having this same problem after disabling Defender and uninstalling my antivirus software. I'm posting this in case anyone stumbles along this page, like I did, in search of answers. What worked for me might not work for them, but I think we all know that any help while troubleshooting is worth at least trying.
TLDR: Run the OculusSetup.exe from somewhere in your C drive and make sure you have at least 30gb of space available.
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Even though the installer says it needs ~9gigs of free space to complete installation of the Oculus App, it did not work unless I had 30gigs available.
I watched my storage change in real time. For some reason the install occupied 27gb, but when it finished it only used 15gb. Not sure why, but that's what happened, so it seems important that there are 30 free gigs before beginning.
Although it might not work for everyone, this was my process in the order I did it:
1. Delete OculusSetup.exe from D :\Downloads folder (yours might not be in D : \ but mine is)
2. Unplug your ethernet cable and disconnect from wifi
3. Reboot Windows into Safe Mode
4. Navigate to
C:\Users\[YourUsername]\Appdata
5. Search for "Oculus" and wait for it to finish
6. Delete everything associated with the word Oculus
7. Repeat steps 4 - 6 for all three folders inside the Appdata folder (these searches will probably show nothing. If so, you're done with this step)
8. Empty Recycle Bin
9. Reboot to regular Windows
10. Plug ethernet back in/enable wifi
11a. Download OculusSetup.exe from their website
oculus . com / setup
And it will show up in your usual Downloads folder
11b. If your Downloads folder isn't in your C:\ drive, go there and locate the OculusSetup.exe file you just downloaded. Right click it, select "Cut" and then paste it anywhere in your C:\ drive.
(Personally I opened my C:\ drive and dropped it right there. To be safe I double checked that the file wasn't still in D : \ Downloads)
12. Run OculusSetup.exe from its new location in the C:\ drive.
13. [Solved]
The important things seemed to be having 30gb of available space and launching the .exe from my C:\ drive.