Hi,
i’ve implemented Grafana as an iframe integration and i successfully seeing the login screen.
but after successfully login the login page is loaded again and i cannot see the dashboard or any other path
both of the machines are running at AWS services (grafana as standalone and web interface as standalone - not on the same machine)
Please advice 
Sorry for reviving this old topic but I was having the same issue and was having trouble finding the solution. What worked for me personally, was going into the grafana.ini (or defaults.ini) and changing the following configurations:
- allow_embedding = true
- cookie_secure = true
- cookie_samesite = none
In the event that someone else get this error in the future, this solution may be helpful.
