have U installed how? PPA or manually downloading the tar.gz package? however, try uninstalling to install again:
if installed by PPA run the following command through the terminal:
sudo add-apt-repository ppa:bitcoin/bitcoin -r -y
sudo apt-get remove bitcoin-qt bitcoind --auto-remove
Once you have uninstalled, please install again by PPA:
sudo add-apt-repository ppa:bitcoin/bitcoin
sudo apt-get update
sudo apt-get install bitcoin-qt bitcoind
if the persister error tries to contact Bitcoin Core developers by github in issues