Rails 4 asset pipeline throws "only generation of JSON objects or arrays allowed"

Question

This may be related to JSON error with coffeescript & Rails asset pipeline

I'm working on an app in Rails 4. I have an asset called tasks.js.coffee. Until recently everything was fine. This morning I wanted to make a change, and Rails throws "only generation of JSON objects or arrays allowed".

It seems that any change is sufficient to throw the error, even removing a blank line, or changing a single character in a string. When I revert changes it works again.

I'm assuming some gems got updated yesterday when I did a bundle update, causing this problem.

Did anybody else see it? Does anyone know what causes this problem, and how to fix it?

Answer 1

Update your ruby version to 2.0.0.

Answer 2

I had to set the execjs version in the Gemfile to 1.4.0: gem 'execjs' '1.4.0'. The recent update to 2.0.0 seems to be the one causing the issue.