GrimLok

So the workaround is to use another launcher or upgrade to the new one? @Devin Weaver - Your Launcher was installed? I just run mine from a Minecraft.jar file and don't have any other files anyware else that pertain to it. I run it the same way on the Windows 7 machine as well.

I can attest to this happening on 3 different computers of mine.  Two have different versions of GNU/Linux (Trisquel on one, xubuntu on another) and one is a Windows machine (Win7).  They all stopped working simultaneously just the other day specifically for 1.14.4, all other versions still work.

I am getting the exact same errors as the original poster.

If any of the advanced users here have figured this out and could clue us in on what reformatting json files is, and what obfuscation map entries are, that would be great.

I suspect that it is something more to do with the launcher version than any file, because the error happens before you even try to load 1.14.4.  And it doesn't effect the newer launcher that has the built in JRE that MS puts out.