PS, when I try closing individual pages, it also stalls.

PPS FF 68.0.1

(no edit function showing Safari, so PS's)

Re-upping this problem. Now problem not happening every time, but most times I crash or restart. I've learned now to wait until pages loaded, then I can more easily close the duplicates. No help last time I submitted, hoping someone might have an answer now. thanks

Mac OS 10.13.6; FF 69.0.3

Hi maveet, sorry you didn't get a reply before.

Are you using only the built-in session restore feature, or are you supplementing/substituting that with an add-on?

Although it's possible to duplicate tabs using built-in features, it isn't something that should happen automatically. That is hard to explain.

Regarding the way you close unwanted tabs:

Firefox normally will only load the tab that was active at the time the window was closed, and other tabs will be loaded on demand. If you activate a tab and then close it, Firefox might need to continue loading for a bit before responding to the close command. If you know a tab needs to be closed, instead of activating it, you could right-click (Ctrl+click) it as a background tab and use Close Tab on the context menu. Maybe that will help?

If your Firefox is configured to load every single tab when a session is restored, you could undo that:

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

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

(3) If the browser.sessionstore.restore_on_demand preference is bolded and "modified" to false, double-click it to restore the default value of true

You can check for problems with the sessionstore.jsonlz4 file in the Firefox profile folder that stores session data.

• delete sessionstore.jsonlz4 and sessionstore.js

When sessionstore.jsonlz4 is deleted you lose pinned tabs and open tabs and you will have to recreate them, so if necessary make a note or bookmark them.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/Profiles

@jscher, I do have session boss extension, though I've never consciously used it. Maybe I should first disable it?

And only the open tabs are loading, the others not activated.

@cor-el thanks, if disabling session boss doesn't rectify things, I'll follow your directions.

Thanks both for responding. I'll se how it goes over the next days. cheers.

First reboot since session boss disabled. Brilliant! Fast and easy loading. I'll wait until I've done this again before notifying problem solved. Thank you. :-)

Such a relief to have windows open quickly and easily, no duplicates. thx.