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Why am I unable to share my screen in WebEx through Firefox?

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  • 1 has this problem
  • 8 views
  • Last reply by Monophoto

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In early October, Microsoft forced my computer to upgrade from Windows 7 to Windows 10. I am a frequent participant in on-line meetings and Webinars using WebEx. Since that upgrade, I can generally still log into a WebEx meeting, but I am unable to 'share my screen' with other participants. My computer tells me that my screen is being shared, but the other participants in the call report that all they can see is a gray box with a faint 'waffle' pattern.

When I log into the conference using Google Chrome or Microsoft Edge, the screen sharing function works correctly. Also, after logging in I can use Firefox to access web sites, and other participants in the meeting can see everything that I am doing. So the problem is limited to those instances when I log into the WebEx conference using Firefox.

I know that there is a known issue that one of the patches Microsoft distributed a year or so ago can cause this symptom. However, there is no evidence that patch was actually installed on my computer.

I've been through a sporadic series of tests with CISCO to determine what is causing this problem. Eventually, they reported that that had found a conflict between both Windows 8 and Windows 10, and the current version of WebEx software, that can cause this symptom with some users. They seemed remarkably unexcited about the problem, and didn't offer any additional details, and have also said that they have decided to do nothing about it until some future release of WebEx software - which leaves me forced to use the workaround of using Chrome every time I need to start a WebEx session.

Has anyone else run into this? Is there a solution other than the workaround of using Chrome?

All Replies (2)

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Does Cisco have a support article about the problem that describes the cause of it?

From the Firefox side, if a plugin is required, there might be an issue with the plugin that generates error messages or warnings in the browser console (Ctrl+Shift+j or access it from the Developer menu).

One other thing you could check...

Multiprocess (e10s)

One of the headline changes in Firefox 48+ is e10s, which separates the browser interface process from the page content process. More and more users are gradually having this multiprocess feature switched on. There are some compatibility issues with this setting that still need to be worked out.

I don't know whether this is relevant to your experience with WebEx, so let's check.

Are you using e10s?

You can confirm you have this feature turned on as follows. Either:

  • "3-bar" menu button > "?" button > Troubleshooting Information
  • (menu bar) Help > Troubleshooting Information
  • type or paste about:support in the address bar and press Enter

In the first table on the page, check the row for "Multiprocess Windows" and see whether the number on the left side of the fraction is greater than zero. If so, you are using e10s.

If you are using e10s:

You could evaluate whether e10s is causing this problem by turning it off as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste autos and pause while the list is filtered

(3) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?

If that doesn't help, I suggest re-enabling e10s for better stability.

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CISCO doesn't have a support article. In fact, it has taken them two months to finally say that they think they may have found the cause, but don't intend to do anything about it anytime soon (which leads me to suspect that they still don't know what the problem is and they are just trying to make me go away).

As far as I can tell, I am not using the e10s feature.