How can I get the logs for Portainer itself?

Portainer runs as a container, so you can view the Portainer logs in the same way you would do for any other container. You can view the logs through the Portainer UI, or alternatively if you have access to the host you can use the Docker CLI:

Log into the command line of a Docker manager node (for Swarm) or the Docker host (for Standalone) and run the following command:

docker ps -a

This will list the containers on your environment, and will look something like this:

CONTAINER ID   IMAGE                          COMMAND                    REATED     STATUS    PORTS                                                                                          NAMES
2c9085c1d664 portainer/portainer-ee:latest "/portainer" 3 days ago Up 3 days>8000/tcp, :::8000->8000/tcp,>9443/tcp, :::9443->9443/tcp, 9000/tcp portainer
be84ee30270e mysql:8.0 "docker-entrypoint.s… " 4 days ago Exited (1) 4 days ago mysql
4604a2f5108e nginx:latest "/docker-entrypoint.…" 4 days ago Up 4 days>80/tcp, :::80->80/tcp                                                            nginx

Note the CONTAINER_ID of the Portainer container. Next, run the following command to output the logs for the container, using the CONTAINER_ID from the previous command (in the above example, 2c9085c1d664):

docker container logs 2c9085c1d664

The logs from the container will be displayed.