For anyone who is still confused about what causes this: Firefox launches copies of itself when creating new website instances (usually when loading a website that has not already been loaded). Because of this, if it is updated in the background (through any means; I usually see this after a manual system update), Firefox has to restart when you try and load a new site because it cannot create any compatible copies of itself, since the old version is the one that is still running and the copies would use the new (updated) version.
The solution is to only update when Firefox is closed, or restart it when it asks.
For anyone who is still confused about what causes this: Firefox launches copies of itself when creating new website instances (usually when loading a website that has not already been loaded). Because of this, if it is updated in the background (through any means; I usually see this after a manual system update), Firefox has to restart when you try and load a new site because it cannot create any compatible copies of itself, since the old version is the one that is still running and the copies would use the new (updated) version.
The solution is to only update when Firefox is closed, or restart it when it asks.
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