Вот тут пишут, что надо проверить параметр tcpip_socket
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To get pgAdmin III working properly with PostgreSQL on your Windows box you need to open up the configuration file:

Program Files\PostgreSQL\data\postgresql.conf

using Wordpad. When the file is open you should see a section designated - Connection Parameters. There is a line there which reads as:

# tcpip_socket = false

Remove the # (which comments out the line) and change the false to true. In other words change the line so that it now reads as

tcpip_socket = true

and save the file. This tells the server that it should also be listening on the TCP socket and not just the UNIX domain sockets(which it does by default).

Then you should open up a command window, and shut down your server using the file: Program Files\PostgreSQL\bin\pgsqlstop.bat

then restart the server using:

Program Files\PostgreSQL\binpgsqlstart.bat
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