Problem solved.
I rebuilded packages from postgresql-9.6beta1.tar.gz source. Made pd-dump and migrated to stable postgres version. Still will be running beta on another port, but not for production anymore.
============ Forwarded message ============
From : <admin@xxxxxx>
To : <pgsql-admin@xxxxxxxxxxxxxx>
Date : Sat, 25 Jun 2016 06:56:17 +0200
Subject : Need older (9.6~beta1-2.pgdg16.04+1) postgres beta packages
============ Forwarded message ============
============ Forwarded message ============
From : <admin@xxxxxx>
To : <pgsql-admin@xxxxxxxxxxxxxx>
Date : Sat, 25 Jun 2016 06:56:17 +0200
Subject : Need older (9.6~beta1-2.pgdg16.04+1) postgres beta packages
============ Forwarded message ============
I need update cluster to new postgres version. The database cluster was initialized with CATALOG_VERSION_NO 201605051, but the server was compiled with CATALOG_VERSION_NO 201606171.
/var/cache/apt/archives was mounted to tmpfs.
Full list of packages I need:
postgresql-common:amd64 174.pgdg16.04+1 postgresql-client-9.6:amd64 9.6~beta1-2.pgdg16.04+1 libpq5:amd64 9.6~beta1-2.pgdg16.04+1 postgresql-9.6:amd64 9.6~beta1-2.pgdg16.04+1 postgresql-client-common:amd64 174.pgdg16.04+1
Or if there is another solution to do cluster upgrade without older packages, I will be glad to hear it.