RE: The application server could not be contacted Error

From: "Nigel Tucker" <nigel(at)specialisedstructures(dot)co(dot)nz>
To: "'Jessica Dow'" <jessrdow(at)yahoo(dot)com>
Cc: <pgadmin-support(at)postgresql(dot)org>
Subject: RE: The application server could not be contacted Error
Date: 2017-11-14 22:51:59
Message-ID: 02e501d35d9b$305c5d70$91151850$
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Hi Jessica,

I am sorry to hear you are having teething troubles with pgAdmin4. I have become quite an enthusiastic user of the package (it took a while!). I am using thing the following (from the Help/About menu):




Copyright 2013 - 2017, The pgAdmin Development Team

Python Version

2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:42:59) [MSC v.1500 32 bit (Intel)]

Flask Version


Application Mode


Current User


This works just fine, and yes it does connect to the three servers I have locally and remotely. The things I like about this version is that it loads in quite a reasonable time now, but most importantly it is stable.

pgAdmin3 had more bells and whistles, but it never, never, never was stable enough for me to have confidence in it. It would certainly crash in Windows 10 every hour or so – which was so annoying. If pgAdmin4 crashes at all, it’s only once a week, which puts it in the random noise category.

The questions Neel asked are vital – if you have any concerns, uninstall your pgAdmin version and try again.

I’ve moved onto postgres 10.0 also and that transition seemed pretty seemless.



Dr Nigel Tucker

System Architect

Specialised Structures NZ

Telephone Direct (NZ) +64 (0) 3 482 2473

SS with Custom

From: Jessica Dow [mailto:jrdow(at)uh(dot)edu]
Sent: Wednesday, 15 November 2017 11:07
To: Anthony DeBarros; Neel Patel; Jessica Dow
Cc: pgadmin-support(at)postgresql(dot)org
Subject: Re: The application server could not be contacted Error

I am on Windows 10. I have clicked through the error message numerous times and re-launched pgAdmin to only get the same message: "The application server could not be contacted". I have even left my computer running for hours to get the same message as well.

On Tuesday, November 14, 2017 12:44 PM, Anthony DeBarros <adebarros(at)gmail(dot)com> wrote:

I’ve experienced this on two Windows machines — one Windows 7 and the other Windows 10. In both cases, if I click through the error message and then re-try launching pgAdmin it will open successfully.

I’ve also noticed that if I attempt to start pgAdmin too soon after booting the machine (and these are both older, slower machines that take a while to boot), then I will get this error. If I let them sit for a bit and do whatever it is that Windows does after booting (seems like a ton of disk activity, maybe some indexing), then pgAdmin is more likely to launch successfully.

On November 14, 2017 at 9:44:35 AM, Jessica Dow (jrdow(at)uh(dot)edu) wrote:

I downloaded the installer of PostgresSQL version 10 and pgAdmin4 came with it, so I'm not sure of the version of pgAdmin4 I am using.

This is the link I used to download the installer: PostgreSQL: Windows installers <>

Yahoo would not allow me to attach the pgAdmin4.log because it is empty.

PostgreSQL: Windows installers

On Tuesday, November 14, 2017 3:25 AM, Neel Patel <neel(dot)patel(at)enterprisedb(dot)com> wrote:


This error will occurred only when python server is not started properly and application try to contact the python server but it fails. It may be due to some error at python backend side or python server taking more time to up.

Can you please provide below information ?

* Which version of pgAdmin4 are you using ?
* Which version of Postgres installers and from where you have downloaded the installers ?
* Can you please share pgAdmin4.log file ?


Neel Patel

On Tue, Nov 14, 2017 at 8:34 AM, Jessica Dow <jrdow(at)uh(dot)edu> wrote:

I was trying to use pgAdmin4 to connect to a database, but I get "The application server could not be contacted. I have tried reinstalling Postgres numerous times, as well using other solutions that were available online, and nothing seems to work. I was hoping you could provide me some assistance to fixing this issue.

Thank you,

Jessica Dow

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