Heroku-builds plugin won't install

Build Environment
1

Running heroku plugins:install heroku-builds during my deploy step has been working great up until a few days ago, when it began to fail. (Output below). Any ideas on how I can get it working again?

My node version is set to 5.1.0. I have also tried it with 5.7.0 with no luck. Oddly, when I SSH into the build and run the exact same command it works! When I look in the /home/ubuntu/.heroku/node-v5.7.0... folder it’s complaining about, everything is there.

I tried manually installing the newest version of the toolbelt but that also did not help. Other plugins seem to install correctly, and the plugin installs correctly on my local machine.

It fails with the following output:

Installing plugin heroku-builds... 
 ▸    Error installing package. 
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    npm ERR! Linux 3.13.0-79-generic
 ▸    npm ERR! argv "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/bin/node" "/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/cli.js" "install" "heroku-builds"
 ▸    npm ERR! node v5.7.0
 ▸    npm ERR! npm  v3.3.10
 ▸    npm ERR! code MODULE_NOT_FOUND
 ▸    
 ▸    npm ERR! Cannot find module '/home/ubuntu/.heroku/node-v5.7.0-linux-x64/lib/node_modules/npm/lib/unbuild.js'
 ▸    npm ERR! 
 ▸    npm ERR! If you need help, you may report this error at:
 ▸    npm ERR!     <https://github.com/npm/npm/issues>
 ▸    
 ▸    npm ERR! Please include the following file with any support request:
 ▸    npm ERR!     /home/ubuntu/.heroku/npm-debug.log
 ▸    
 ▸    Try running again with GODE_DEBUG=info to see more output.

heroku plugins:install heroku-builds returned exit code 1

! error installing plugin heroku-builds Action failed: heroku plugins:install heroku-builds
2

You are not alone, I have just ran into this problem as well. unbuild.js should come with npm, not sure why it is missing.

3

Thanks for chiming in @zbyte64. I had a long thread with CircleCI support about this and here is the solution they helped me come up with. I guess this has something to do with the Heroku Toolbelt installation on the current container image being faulty.

In the post-dependencies block:

Workaround for broken Heroku Toolbelt until the CircleCI container

is updated.

post:
- sudo apt-get purge heroku-toolbelt
- rm -rf ~/.heroku
- sudo apt-get install heroku-toolbelt
- heroku plugins:install heroku-builds