ESR receives regular, every 6 week security updates. It doesn't receive all security updates that regular Firefox does, but it does receive all major and critical security patches. Once a year it receives a full update that catches it up to where regular Firefox is in terms of UI and web features. It also doesn't receive full support from Mozilla and is meant only for enterprises with their own IT departments that can help users with questions.

Regular release receives all new web features and and UI changes every 6 weeks.

If you are going to be developing for regular end-users focus on regular release. ESR doesn't get far enough behind to really worry about for most people (unless there is a specific feature you are developing with). Plus ESR has a fairly insignificant audience.

If you are focusing on enterprise, I'd find out what your users will be using first.

See also the developer release notes:

• https://developer.mozilla.org/Firefox/Releases
• https://developer.mozilla.org/Firefox/Releases/31

• https://developer.mozilla.org/Firefox/Releases/35
• https://developer.mozilla.org/Firefox/Releases/35/Site_Compatibility

Hi Tyler Downer,

Thanks for your quick reply.

I am focusing on enterprise. My web app use the Qooxdoo framework to render GUI.

Some my customers want to use the Firefox ESR to view the web app, so we need make sure that it also works well on Firefox ESR. I need more information about Firefox ESR.

Are there any difference about core or how to render GUI between regular Firefox and Firefox ESR?

If we support Firefox ESR, what do we need to care about?

Thanks and best regards.

Firefox ESR releases are based on a Firefox Release and just get security and allowed stability fixes. The Firefox 31.0.*ESR is based on Firefox 31.0 Release. The next major ESR will be based on Firefox 38.0 Release as it has been every seven ever since Firefox 10.0.