Im trying to install plugin "teamcity-artifactory-plugin-2.1.5.zip", I put the file under teamCity plugin folder as required and start the TeamCity Agent\ Server services.
I can see that the other plugins deployed but this one deleted with any action.
In log file I notices the warning: jetbrains.buildServer.AGENT - Failed to parse teamcity-plugin.xml from plugin: F:\TeamCity\buildAgent\plugins\teamcity-artifactory-plugin-2.1.5.zip. Failed to parse plugin descriptor. Error on line 19: cvc-elt.1: Cannot find the declaration of element 'teamcity-plugin'.
My teamCity version - TeamCity Professional 7.1.3 (build 24266).
It looks like you placed the plugin in the "$TEAMCITY_DATA/buildAgent/plugins" folder instade of "$TEAMCITY_HOME/plugins/".
Once you'll place it in the "$TEAMCITY_HOME/plugins/" it will, after starting Teamcity, unpack the zip and you can start working.