undefined symbol: PQcancelStart

On Fri, 2025-06-20 at 13:49 +0200, Peter Röthlisberger wrote:

Hello all,

Platform: Rocky Linux release 9.4 (Blue Onyx)

I try to migrate from version 16.7 to 17.5. When executing pg_upgrade —check I get the following:

could not load library "$libdir/dblink": ERROR:  could not load library "/opt/postgresql-17.5/lib/dblink.so": /opt/postgresql-17.5/lib/dblink.so: undefined symbol: PQcancelStart
In database: zen_dev1
In database: zen_prod2
could not load library "$libdir/postgres_fdw": ERROR:  could not load library "/opt/postgresql-17.5/lib/postgres_fdw.so": /opt/postgresql-17.5/lib/postgres_fdw.so: undefined symbol: PQcancelStart
In database: zen_dev1

I  tried hard to find a hint on the net. No success hence my first post here. I was able to execute the update on another server having the same OS.

How did you install "dblink.so" and "postgres_fdw.so"?
It looks like you copied them from the old installation. That won't work.

Yours,
Laurenz Albe

Hello Laurenz, thanks for your quick reply.

The issue was having the old postgres library in LD_LIBRARY_PATH. Once I removed it, everything started to look good! In all the past years this was not a problem though. But anyway: All good now!

Thanks again: peter

On 20 Jun 2025, at 14:00, Laurenz Albe <laurenz.albe@cybertec.at> wrote:

On Fri, 2025-06-20 at 13:49 +0200, Peter Röthlisberger wrote:

Hello all,

Platform: Rocky Linux release 9.4 (Blue Onyx)

I try to migrate from version 16.7 to 17.5. When executing pg_upgrade —check I get the following:

could not load library "$libdir/dblink": ERROR: could not load library "/opt/postgresql-17.5/lib/dblink.so": /opt/postgresql-17.5/lib/dblink.so: undefined symbol: PQcancelStart
In database: zen_dev1
In database: zen_prod2
could not load library "$libdir/postgres_fdw": ERROR: could not load library "/opt/postgresql-17.5/lib/postgres_fdw.so": /opt/postgresql-17.5/lib/postgres_fdw.so: undefined symbol: PQcancelStart
In database: zen_dev1

I tried hard to find a hint on the net. No success hence my first post here. I was able to execute the update on another server having the same OS.

How did you install "dblink.so" and "postgres_fdw.so"?
It looks like you copied them from the old installation. That won't work.

Yours,
Laurenz Albe

Peter Roethlisberger
Senior System & Database Architect
Zen Innovations AG
Bernstrasse 99
3122 Kehrsatz
Switzerland
46°54’57” N 007°28’03” E

www.zen-innovations.com
Phone: +41 (0)31 550 07 65
Mobile: +41 (0)79 785 79 35
D-U-N-S® Number: 48-405-0989
peter.roethlisberger@zen-innovations.com