This is actually the only thing that worked for me! I’m on 4.18.2 and using Visual Studio 2017. I think it matters which version of Visual Studio 2017 you’re using cause my PC has it installed and this issue only pops up on my laptop, which has newer version.
Where did you find this folder? I can see only Wmfedia folder but no WFMedia.
Engine/Plugins/Media/WmfMedia 
The above was a typo, sorry.
Updating my Visual Studio for the 4.20 engine caused my 4.19 projects to break with this error. I tried all of the solutions, and none of them worked for me.
Searching on Discord, I found a post from Joshua who said:
Removing Wmfmedia plugin completely fixed it.
This worked. Thanks Joshua!
This worked for me on UE 4.20.2 ,Visual Studio 2017 14.15.26726 toolchain.
This didn’t work for me in 4.16.
Thank you! This solved my problem! (UE4.16.3 VS2017)