When Firefox 10 was released, this version was also released as an ‘ESR’ ( or Extended Support Release ) build. ESR releases of Firefox are intended for deployments of Firefox within large organizations and are supported for much longer periods of time. For more information on ESR, please see the proposal on the wiki:
If you intend to develop add-ons using the SDK specifically for ESR users there are some limitations and caveats you should be aware of. As the Development Process page on the Jetpack wiki states:
SDK Released Version: An SDK in the Release state is compatible with the Release Firefox and the Beta Firefox at the time of the SDK’s release.
For add-ons targeting the ESR release specifically, this means that you will need to use SDK version 1.5 to package add-ons for Firefox 10 ESR users. As well, xpis created with SDK 1.5 may not be compatible with future versions of Firefox; the SDK team does not intend to back-port support for future versions of Firefox to SDK 1.5. We will however continue to evaluate critical security and stability issues for inclusion in a potential 1.5 patch release; we have no current plans to do a patch release at this time.
We will continue to update you on future SDK 1.5 and ESR-related compatibility issues via this blog. If you have any comments regarding this, please post to this thread in the Jetpack google group.