CircleCI only supports Ruby versions written in the official documentation.

• Test environment - CircleCI

I had specified only ruby-1.9.3 in the .ruby-version file, and when the patch level was updated but CircleCI didn’t support it yet, I got errors and tests failed.

Unless there’s a specific reason not to, specify down to the patch level like this:

ruby-1.9.3-p547

Reference Information

・CircleCI uses the wrong Ruby version - CircleCI

・Configuring CircleCI - CircleCI

That’s all from the Gemba.