Blender to Unity import errors

You all have probably heard about the import errors people are getting when importing .blend files to Unity 2019 with Blender 2.79 and under.
This also happens vice versa with Unity 2018 and under unable to import .blend files from Blender 2.8

I have been using 2017 and Blender 2.79 for the past few months witthout any problems. I choose not to import to Unity as .fbx as i find it bothersome. When Blender 2.8 came out I decided it was time to update as I really liked the new UI. I created a new project in 2018
(Yes 2018 not 2017, i was starting a new project and wanted to try the nested prefabs). Everything went fine until I imported a Model made with blender 2.8.

It gave me the "Could not Import .blend file etc" error. The solutions i could find online was to either update to Unity 2019 or change the BlendToFbx.py file.

At first I tried changing the BlendToFbx.py file of Unity 2018 to the one from 2019 (someone sent it to me) but it did not work and the error was still present.

So I updated to 2019. Everything went fine in the new project with me using 2019 and .blend files from 2.8

But today I figured Id work on the old project again (the one on Unity 2017)
I downloaded Blender 2.79 again as a .zip as it got overwritten by Blender 2.8 before
The game worked fine and all .blend files were present when the editor loaded.
But when I imported a .blend i made with 2.79 to Unity 2017. It gave me the error. Note : it was only for that new .blend i imported in and not the other .blends and when i DO open those other .blends in 2.79 and simply save them. It gives me the error in Unity. (Oh and sorry if i didnt state this before but all the .blends are in the assets folder of Unity)

I was so confused because Ive been using this setup for so long with no problems. Does this have something to do with me updating to 2019 or installing Blender2.8?
I am pretty sure i did not mess with the 2017 BlendtoFBX.py file either.

I am really scared as this project has a lot of .blend files and i might lose them (of course i have back them up but still what if i cant use them again)