Firefox ESR Release Calendar

The linked table shows the support lifecycle for Firefox Extended Support Releases (ESR) which we sometimes need to support for enterprise customers.

The ESR cadence works something like this:

• Firefox ESR freezes the then-current Firefox version for a year.
• During this year Mozilla backports security patches to the current ESR, but does not add features.
• Two subsequent ESR releases overlap for three months. This way enterprises have a quarter to test the new version and migrate their clients.