sass-rails: Error encountered while saving cache ... can't dump hash with default proc

Martin, I’ve checked your test project with mine. The issue is related to the import of the google font:

@import url(http://fonts.googleapis.com/css?family=Hind:300,700)

If you remove that import you stop receiving the warning. I’ll be checking the documentation to see if we are doing something wrong or if there is a reported bug related to it. I’ll let you know if I have any luck.

Hit this error today as well

sass (3.4.22)
sass-rails (5.0.6)
  railties (>= 4.0.0, < 6)
  sass (~> 3.1)
  sprockets (>= 2.8, < 4.0)
  sprockets-rails (>= 2.0, < 4.0)
  tilt (>= 1.1, < 3)

The fonts still render in the browser but are excluded from the cache. It’s not a huge performance hit per request, but it adds up.

We are not using active_skin or middleman, just plain old sass with google fonts:

We’ve tried the following variations with no joy:

@import url(https://fonts.googleapis.com/css?family=Montserrat:400,600,700|Open+Sans:400,600,700)
@import url(http://fonts.googleapis.com/css?family=Montserrat:400,600,700|Open+Sans:400,600,700)
@import url("http://fonts.googleapis.com/css?family=Montserrat:400,600,700|Open+Sans:400,600,700")
@import url(//fonts.googleapis.com/css?family=Montserrat:400,600,700|Open+Sans:400,600,700)

Commenting the @import line out stops the error but of course does not use the desired fonts.

UPDATE: downloading the .css file directly for https://fonts.googleapis.com/css?family=Montserrat:400,600,700|Open+Sans:400,600,700, saving it in a .css file and importing that instead does work around this error.