On Wed, 22 Nov 2017, Dan wrote:

> On my SL7.4 laptop, I have docker-pr listening for https connections.
> (Within docker, I have a locally-compiled copy of elabftw running an
> electronic lab book service.)
> When I point my web browser (Firefox) on the same machine to
> https://localhost, I initially get a "Your connection is not secure"
> warning.  That's not surprising, because my certificates are not
> signed by anyone else.  So, I choose the "advanced" button then the
> "add exception" button (with "permanently store this exception"
> unchecked) to go ahead and connect.
> After this, all sometimes works smoothly - I arrive at the elabftw
> login screen and can carry on and use my electronic lab book.
> However, on other occasions, I get the message "502 Bad Gateway:
> nginx" and am unable to connect to the electronic lab book.  I'm not
> aware of having done anything differently in the two types of case.
> Does anyone have any idea what might explain the two different
> behaviours, please?

To answer my own question ... on trying a web search engine other than
my usual one, I was able to find a known explanation for, and solution
to, this problem, at <https://github.com/elabftw/elabftw/issues/333>.