User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0 (Beta/Release) Build ID: 20131205075310 Steps to reproduce: NB: I know this feature is experimental; I just want to help by giving some feedback. I followed the instructions here to test: http://billmccloskey.wordpress.com/2013/12/05/multiprocess-firefox/#trying I tried to install HTTPS Everywhere here: https://www.eff.org/https-everywhere (It's not available on the extension "store"). Actual results: The link on the page to install the extension doesn't do anything. Expected results: Propose the installation of a new extension

Thanks, Romain. I see the same problem on OS X: onPacket threw an exception: Error: Server did not specify an actor, dropping packet: {"error":"unknownError","message":"error occurred while processing 'startListeners: Error: cannot ipc non-cpow object\nStack: CPL__init@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/toolkit/webconsole/utils.js:2571\nCPL_startMonitor@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/toolkit/webconsole/utils.js:2600\nWCA_onStartListeners@resource://gre/modules/devtools/dbg-server.jsm -> resource://gre/modules/devtools/server/main.js -> resource://gre/modules/devtools/server/actors/webconsole.js:492\nDSC_onPacket@resource://gre/modules/devtools/dbg-server.jsm -> resource://gre/modules/devtools/server/main.js:1021\nLDT_send/<@resource://gre/modules/devtools/dbg-server.jsm -> resource://gre/modules/devtools/server/main.js -> resource://gre/modules/devtools/server/transport.js:258\nmakeInfallible/<@resource://gre/modules/devtools/dbg-server.jsm -> resource://gre/modules/devtools/server/main.js -> resource://gre/modules/devtools/DevToolsUtils.js:76\n"} Stack: DC_onPacket/<@resource://gre/modules/devtools/dbg-client.jsm:668 resolve@resource://gre/modules/commonjs/sdk/core/promise.js:118 then@resource://gre/modules/commonjs/sdk/core/promise.js:43 then@resource://gre/modules/commonjs/sdk/core/promise.js:153 DC_onPacket@resource://gre/modules/devtools/dbg-client.jsm:717 LDT_send/<@resource://gre/modules/devtools/dbg-server.jsm -> resource://gre/modules/devtools/server/main.js -> resource://gre/modules/devtools/server/transport.js:258 makeInfallible/<@resource://gre/modules/devtools/dbg-server.jsm -> resource://gre/modules/devtools/server/main.js -> resource://gre/modules/devtools/DevToolsUtils.js:76