Error Messages page StealJS.error-messages The following are common error messages that occur within StealJS apps. This guide lists some of the most common types of error messages and provides some advise on how to track down where the problem is in your code. 404 Not Found This error occurs where requesting a module fails because the web server returned a 404 status code. The cause of this error could be: The file hasn't been created (or saved) yet. There is a typo in the import statement. Click the link in the stack trace (app.js:6 in the above screenshot) to take you to the code in the debugger to see. If the module being imported is from a 3rd party dependency, you might have forgotten to save the dependency in your package.json's dependencies list. Mismatched package version This error occurs when a dependency is not found for the requested version range. In the above example the canjs package is a dependency of dep. The semver range of ^4.0.0 is requested but 5.0.0 was found, which does not satisfy the range. This error usually occurs changing versions and forgeting to run npm install.