I know the guidelines, however in this case Im not sure what you need me to do, the video I attached shows very clearly what I did, which is try to use the functions of the F2 addon, by trying to create a quad from a vertex by clicking the key "F"

A detailed description of what I did follows, which is me describing what I did on the video, the video is much better at showing the problem, the problem is super easy to see on the video, even the error window is shown there, I actually think me describing the steps makes things more cumbersome.

I attached an .blend file and a zip of the build of blender I used, with a cube that is ready to be used to test the F2 addon

1.- Unzip the blender build included in this message.

2.- Unzip the .bled file included on this message

3.-Click the blender.exe of the build included in this message.

4.-Revert to factory settings

5.-Got to preferences and activate the F2 addon

5.-open the .blend file included on this message.

6.-using the currently selected vertex, try to create a quad using the "Vertex to Quad" function of the F2 addon

"Quad from vertex"
When a single vertex is selected, a new quad is created by creating a new vertex. The position of this new vertex is calculated based on the three existing vertices. These are the selected vertex, and two vertices to which it is connected via open edges. An open edge is an edge which is only part of one face, or none at all. The newly created quad has the same material and normal direction as the neighbouring faces.

3.-Nothing happens, no quad is created, and an error window appears that reads:
Traceback (most recent call last):

File "C:\Program Files\Blender Foundation\blender-2.79-980a864-win64\blender-2.79.0-git.980a864-windows64\2.79\scripts\addons\mesh_f2.py", line 359, in invoke
  quad_from_vertex(bm, sel[0], context, event)
File "C:\Program Files\Blender Foundation\blender-2.79-980a864-win64\blender-2.79.0-git.980a864-windows64\2.79\scripts\addons\mesh_f2.py", line 270, in quad_from_vertex
  face.smooth = smooth

SystemError: error return without exception set

7.-Exit edit mode and the face that should have appeared in edit mode suddenly is there.

Please check the latest build if the error is fixed.
There was an regression in the latest master (see T52517 and the commit related to it).

@Paul J. Schrenker (pauljs75) Please check the latest build from https://builder.blender.org/download/

Hi, The problem is gone, :) thanks a lot, however in today's build the addon "loop tools" is not working.

blender-2.79.0-git.dcebad7-windows64

1.-start blender

2.-revert to factory settings

3.-click on activate the addon "loop tools", and it will give you an error.

4.-even if its marked as being "on" (it gives you an error when you try to do so, but the tick that shows if the addon is active or not gets ticked on),
it does not appear in the "W" specials menu.

If you wish me to I create a ticket for this I can do it.