Unable to receive image on email-alert

hi guys ,
after upgrading Grafana from 6.6 to 7.1.5 i found myself unable to receive images and i got that error ''No image renderer available/installed ‘’
so i installed image renderer-plugin on grafana using that command
‘‘grafana-cli plugins install grafana-image-renderer’’
but i got that error ‘‘Failed to read plugin provisioning files from directory" logger=provisioning.plugins path=…r directory"
sept. 18 12:21:19 grafana.si.com systemd[1]: Started Grafana instance’’
how can i solve that please ? !