, Add the following lines in terminal: , wget -O - http://qgis.org/downloads/qgis-2017.gpg.key | gpg --import , gpg --fingerprint CAEB3DC3BDF7FB45 , , Should output: , pub 2048R/BDF7FB45 2017-08-16 expires: 2019-08-16 , Key fingerprint = 61E0 A086 749E 463E DE50 2255 CAEB 3DC3 BDF7 FB45 , uid QGIS Archive Automatic Signing Key (2017) qgis-developer@lists.osgeo.org , sub 2048R/E959BBCF 2017-08-16 expires: 2019-08-16 , , then add: , sudo apt-get update , gpg --export --armor CAEB3DC3BDF7FB45 | sudo apt-key add - , sudo apt-get update (again to see if there are still any errors) , , sudo apt-get install qgis python-qgis qgis-plugin-grass ,