Bug 787253 was caused by using the .checkCompatibility setter before the AddonManager had initialized. This isn't a problem on normal Nightly builds, as PREF_EM_CHECK_COMPATIBILITY is set when AddonManager.jsm is loaded when running on the nightly channel. This isn't the case for non-nightly channels such as aurora, beta, release, esr. So similar to bug 782881, that setter should have a guard in place, so it's guaranteed to work consistently for all channels.

Ended up doing this for all setters/getters, since their values are all initially set in startup(), and we stop observing pref changes after shutdown(). And it doesn't really make sense to allow using their setters when the getters won't work. test_shutdown.js now fails without the patch for bug 787253 (currently on fx-team).

Comment on attachment 658391 [details] [diff] [review] Patch v1 Review of attachment 658391 [details] [diff] [review]: ----------------------------------------------------------------- ::: toolkit/mozapps/extensions/test/xpcshell/test_shutdown.js @@ +54,5 @@ > + } > + if (typeof desc.set == "function" && aIgnore.setters.indexOf(prop) == -1) { > + do_print(aObjName + "." + prop + " setter"); > + try { > + obj[prop] = "i am the walrus"; r++

Aaaaand backed out, thanks to debug-only xpcshell orange. I forgot to add __AddonManagerInternal__ to the ignore list :\ https://hg.mozilla.org/integration/fx-team/rev/ff05869f99ba

Relanded, with that property ignored, and after a successful Try run: https://hg.mozilla.org/integration/fx-team/rev/9a02263d7206

Backed out under suspicion of somehow causing top-crasher bug 792825: https://hg.mozilla.org/integration/mozilla-inbound/rev/fc074c415513 https://hg.mozilla.org/mozilla-central/rev/fc074c415513

Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.