I have tried this for the error
array ( 'code' => 'Gone', 'message' => 'The API version \'V2\' has been deprecated.', )
Update the callback() method, run this caommand inside plugin directory "php -r '$phar = new Phar("auth-oauth2.phar"); $phar->extractTo("./auth-oauth2");" , update the table ost_plugin install_path to plugins/auth-oauth2 and ispher 0.
Still the error persistent. osTicket (v1.18)
Anything else to try please ?