Site was unable to upgrade automatically (clicking on upgrade link in ATS) reason given was unable to read .zip file
Installing the upgrade manually through the Extensions - Install process resulted in the following error:
JInstaller: :Install: File does not exist /home/xxxxxx/public_html/tmp/install_52cc00ea9623d/plugins/ats/sociallike/language/en-GB/en-GB.plg_ats_sociallike.ini