Application Server Error in pgAdmin 4 on macOS

Introduction

For Mac users who have upgraded to macOS High Sierra, opening pgAdmin 4 may result in the "Application Server" error. This error occurs when the pgAdmin 4 server cannot be contacted.

Troubleshooting Steps

To resolve this issue, follow these steps:

1. Check Configuration Settings

Open the pgAdmin 4 configuration file (usually located at /usr/local/etc/pgadmin4/pgadmin4.conf) and check the following settings:

• Ensure that webserver_address is set to 127.0.0.1 or the IP address of your computer.
• Make sure that webserver_port is set to the correct port number (usually 80).
• Check if the ; at the beginning of the python_use_display line has been removed.

2. Restart pgAdmin 4 Server

Once you have made the necessary changes to the configuration file, restart the pgAdmin 4 server by running the following command in the terminal:

 pg_ctlcluster 14 main restart 

3. Other Possible Causes

If the above steps do not resolve the issue, other possible causes include:

• The pgAdmin 4 server is not running.
• There is a firewall preventing communication with the server.
• The pgAdmin 4 installation is corrupted.