This was a big headache for me when I upgraded to Ubuntu 8.10 from Ubuntu 8.04, that my Firefox Web browser happened to go off-line whenever I connected to the Internet using my home Internet connection. But it worked perfectly when I connected from the university or using other wireless access points. After googling for few minutes, I was able to find what went wrong for me. It was something to do with Firefox configuration for not to check the network management applet in Linux for available networks, whenever Firefox connects to the Internet. Though this bug is reported, it is not been handled nor assigned to anybody at BugZilla, so it is still remains as a bug in Firefox under Linux, unless you run this fix.

Usually with the introduction of Firefox 3, the developers have developed the famous Web browser in a way that when it runs under Linux variants, it checks the network management applet to check whether the computer has already been connected to a network and adjusts its mode of operation according to that, meaning Firefox will operate in on-line mode only if the Linux box is connected to a network. But the network manager comes with Linux has some issues with identifying PPP connections that uses USB modems to connect to the Internet. Due to this erroneous behavior of the network management applet, it tends to complain by saying it is not connected to a network though you are connected to the Internet using your USB ADSL modem (ZTE ZXDSL 852 in my case). Now with this erroneous behavior if you are using Firefox 3, since Firefox checks the network management applet for available networks, it will fail to recognize that you are connected to the Internet as network management applet fails to detect your ADSL Internet connection. This causes Firefox to operate in off-line mode, so you will be not be able to browse the Internet.

The easiest way to fix this issue is by changing your Firefox browser settings to not to check the network management applet before connecting to the Internet. This can be done in few easy steps:

  1. First open a new Firefox Web Browser and type about:config at the address bar. Then you'll get a page saying changing advanced settings can harm your computer, believe me, this won't do any harm. Just click on the button "I'll be careful, I promise".
  2. Now type "toolkit.networkmanager.disable" at the filter bar you get there, which will show you the Firefox setting for toolkit.networkmanager.disable property. In your case, this should be set to false.
  3. Now double click on toolkit.networkmanager.disable which will set toolkit.networkmanager.disable's value to true. Thats all you have to do. Now restart Firefox.

toolkit.networkmanager.disable is the Firefox setting which allows you to control Firefox's communication with network management applet in Linux. Setting this property's value to true makes Firefox to not to use network manager to detect on-line/off-line status. Therefore if the network management applet controls active network connections incorrectly, this setting lets you avoid the problems caused due to such issues with network manager and guide Firefox to use its status as on-line. So you won't get "work off-line error page" while you are connected to a network.

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    I.N Rockz said...

    bro is dis wrkng 4 ubuntu 9.0.4

  1. ... on May 3, 2009 at 12:25 AM  
  2. SanJ Wijeratne said...

    Well, I couldn't install or upgrade to Jaunty yet so I'm not sure whether that bug with the network manager is fixed or not, but anyway it won't do any harm by setting toolkit.networkmanager.disable's value to true I guess ;-) so if u r using Ubuntu 9.04 by now, just give it a try and let me know also ;-) else will update you once I get my Ubuntu box upgraded to Jaunty :-)

  3. ... on May 3, 2009 at 2:04 AM  
  4. I.N Rockz said...

    somtyms ubuntu break up due to som hardware failures too coz im xperienced on dat.once i tried to install ubuntu 8.10 but i coudnt install @ least i coudnt try without installing coz ubuntu has som hardware issues but ubuntu 9.0 has fixed it & i started using it but stil som direct parelel & WAN/ATM ports get disabled stil i think da problem has not fixed

  5. ... on May 3, 2009 at 4:28 AM  
  6. SanJ Wijeratne said...

    Bro, this issue is not fixed in Jaunty yet. I yesterday upgraded to Jaunty and tried to access the Internet using my ADSL USB modem. Unless you set toolkit.networkmanager.disable=ture you can't surf the Internet as browser claims that it is working under Offline mode.

  7. ... on May 29, 2009 at 4:57 PM  
  8. MCAndre said...

    I got fed up with this problem and just made an add-on to fix it.

    Always Online

  9. ... on July 29, 2009 at 12:16 PM  
  10. SanJ Wijeratne said...

    @MCAndre - A cool plugin, Always online ;-). Actually I found it while finding ways to fix this issue, but since it was installing another application on top of Firefox, I thought of modifying the config file. I hope the underlying implementation must be somewhat similar. Anyway thankx for the comment ;-)

  11. ... on July 29, 2009 at 2:46 PM