问题
I have installed version 4-1.5, but when opening it, it always shows this error "The application server could not be contacted."
回答1:
I removed the local directory hidden and resolved:
$ cd ~
$ rm -r .pgadmin/
Note: macOS Sierra (10.12.6) and pgAdmin 4-1.6. Also you are going to loose configuration data like database list tree, et al.
The Databases will remain intact since you are modifying/deleting PgAdmin related data not any of Postgresql itself.
回答2:
I had the same issue, I fixed it by stopping the service in Postgres app, then start pgAdmin, and then start the Postgres service. I was able to connect it after that. Hope this help.
回答3:
I had same error, but in my case I use wrong port number for the database
回答4:
On my system Safari is the problem as it was default browser.
To fix, make Chrome your default browser and try relaunching pgadmin4
OR
Manually fix by $ cat ~/.pgAdmin4.5704814747986328352.addr http://127.0.0.1:62631/?key=0ec25e6a-dfe2-483e-9814-b315ea87c3cf
Paste what you get in Chrome
来源：https://stackoverflow.com/questions/44101231/error-when-opening-pgadmin-4-on-mac