Try removing the key with:
sudo apt-key del 0FAD31CA8719FCE4
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Quote:gpg: invalid key resource URL '/tmp/apt-key-gpghome.YystWWMZhF/home tevenpusser.asc.gpg'
tevenpusser.asc.gpg'
gpg: keyblock resource '(null)': General error
OK
 
ls /etc/apt/trusted.gpg.d/
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Quote:home tevenpusser.asc            ubuntu-keyring-2012-cdimage.gpg
tevenpusser.asc            ubuntu-keyring-2012-cdimage.gpg
ubuntu-keyring-2012-archive.gpg  ubuntu-keyring-2018-archive.gpg
 
Delete the home

tevenpusser.asc key as Administrator 
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That worked!
Thank you so much!
 
No problem. Looks like you've added the palemoon browser at some point and the key was added incorrectly. If that is the case, get the binary packages instead. 
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That is exactly it!
I will just get the binary from now on.
 
Great. Please mark the thread as Solved. See Forum Guidelines for how to. 
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