Comment 18 for bug 1830096

For what it's worth, my kids encountered this on two desktops today, moving from 16.04 to 18.04. As this would be a major issue for non-technical folk I'd urge getting the fix out the door sooner rather than later - especially on 18.04, to preserve LTS as being a safe choice.

The workaround I used here, prior to being shown this bug, was to let Firefox make a new profile and to follow these instructions to copy over all the critical files:

    https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile