JHipster introduced a nice upgrade utility since version 3.4 but it seems it has some issue when you work in Ubuntu.
This is a workaround to get it working
First you have to upgrade your NodeJS and npm version to {"node":">=4.4.0","npm":">=2.14.2"}
To do this in Ubuntu you have first to remove the previous version with:
Then install the newest version with
Ok i know `curl to sudo bash is bad in many ways` but this one works.
If you try `yo jhipster:upgrade` and you end up with errors in write access, here comes something also `bad` but it works.
Now go to your project folder and run `yo jhipster:upgrade` and you are ready.
If you have a better solution please let me know.