What is a Runtime Version?

Colab runtimes come with many libraries, packages, and binaries pre-installed. We update these frequently in order to provide users with new capabilities and bug fixes. Runtime Versions refer to past versions of the Colab runtime.

Why would I want to use a past runtime version?

Generally, we recommend using the latest runtime version, which all notebooks are configured to do by default, and adding code to your notebook to install specific versions of libraries that you need. However, some users may want to instead pin their runtime to a past version, for reasons such as the following:

• Their notebook is used by a wide audience, such as in a class or workshop, and they want to ensure that Colab updates do not break their notebook.
• Colab updates a core dependency that cannot be changed back, such as the Python version.

Note that pinning to a past runtime version comes with the following caveats:

• It can take 2-3 minutes to connect to a past runtime version, instead of the few seconds it takes to connect to a default runtime. This is because we need to download the past version image and restart the runtime.
• Some newer Colab features that rely on newer changes to the runtime may not work with past runtime versions.

How can I use a past runtime version?

You can use a past runtime version by selecting it from the Runtime -> Change runtime type dialog, with the "Runtime Version" dropdown.

How long does a past runtime version stay available?

Currently, past runtime versions are available for 1 year after their release.