Heroku CLI installation error: "PATH not updated, original length 1585 > 1024"

I just came across with the same problem. The solution I used is similar to selflearningcode but instead of setting a system variable which failed, I set a user variable.

Try this after selflearningcode's answer, if you can echo %PATH% and it displays heroku you should be good to go. Else, set a user variable on the same screen by adding a new entry to the path and it should work.

Note: Start a new terminal for the effects to be visible.

I may be too late to answer this question but I'll share what worked for me, in case some one else ran into the same issue. Basically, with time my path variable had too many variables added to it, and apparently, there is a characters limit that can be added to the PATH variable. I deleted a few variables in the PATH that I do not need anymore, and that was all!

The Installer is trying to apply an environment variable to the Path. But there are already too many variables setup. Delete the ones that you no longer require and it should work. You could access the System Environment variables by visiting- Settings->Advanced System Settings->Environment Variables