Broken after upgrade

> I am left today, after an upgrade I think (Fedora 23 --> 24) with a
> broken postgresql.
>
> It used to work very well. The service is started with the systemd
> unit file. I have now this error:
>
> -----------------
> postgres(at)thetradinghall 筐､筐､ systemd/system %
> /usr/libexec/postgresql-ctl start -D /db/pgsql/data -s -w -t 270
> FATAL: 22023: database files are incompatible with server
> DETAIL: The data directory was initialized by PostgreSQL version 9.4,
> which is not compatible with this version 9.5.3.
> -----------------------
>
> Googling it gave me some entries, but I couldn't find any clear
> explanation and how to solve. It seems I need to initiate a new
> database, but thereafter is not clear (how to use my old data and conf
> files pg_hba and pg_ident).
>
> Thank you for hints/links how to solve this issue.
> —

I did this also ;(

You might have to remove the 9.5.3 postgresql rpms and install
the 9.4 postgresql rpms.

You can then do a pg_dumpall to get a portable dump of your
database ( if it is not too large ).

You can then reinstall the 9.5.3 rpms and create a new database
with the dump.

Fortunately I had a clone of my db on another machine so I was
able to copy the pg_dumpall from the other machine and recreate
my database.

Jerry