Make sure you have the latest version of Node

Ensure you have the latest stable version of Node as stated on http://nodejs.org/.  

Uninstall old versions

If you installed StrongLoop software prior to Aug. 6, 2014, you must uninstall and then re-install the software.  See Updating to the latest version.

Make sure you have sufficient file privileges

Windows issues

Cygwin not supported

LoopBack does not support Cygwin (Windows bash shell emulator), because Node does not support it for interactive prompts. Use Windows command shell instead.

Installation errors

If you want to use LoopBack and the slc loopback command-line tool on Windows, but encounter installation errors running npm install -g strongloop, use the following workaround:

$ npm install -g yo
$ npm install -g generator-loopback

Then,  instead of slc loopback, use yo loopback instead, including for all the generators, for example yo loopback:model.  For more information on Yeoman, see http://yeoman.io/.

Xcode license issues

If you see errors such as:

Agreeing to the Xcode/iOS license requires admin privileges, please re-run as root via sudo.

Then you recently upgraded or installed Xcode and haven't agreed to the license yet. 

Enter the following command to validate your Xcode license, then reinstall StrongLoop:

$ sudo xcode-select

Errors with npm

Peer dependency errors

If you encounter peerDependency conflicts with modules that are already installed globally either through npm install -g or npm link, you may have conflicting versions of modules installed globally. Inspect your global Node module directory (typically /usr/local/lib/node_modules), remove the conflicting modules manually, then re-install.

Firewall issues

A firewall may block npm installation because it blocks git:// URLs.  You can configure Git to use HTTPS instead as follows:

$ git config --global url."https://".insteadOf git://

See Git is blocked, how to install npm modules (StackOverflow) for more details.

Alternatives to public npm registry

Occasionally, the npm package manager will be down or otherwise generate error messages during installation.  When this occurs, you can wait for the npm problem to be resolved, or:

 Use alternative registry

In addition to the official npm registry at http://registry.npmjs.org, there are several alternative npm registries:

The unofficial registries are not always updated in realtime but may work when the official npm registry is down or overloaded.  You can use npmrc to manage different configurations.

To install StrongLoop software from a different registry:

$ npm —registry <registry_URL> install strongloop

One you have installed slc, you can do more sophisticated registry management using the slc registry command.  See Using multiple package registries for more information.

Install modules from Github

As a last resort, you can search the name of your package on GitHub and either clone with git clone or download the tarball, unzip and copy it in your node_modules folder.