Re: undefined symbol: PQcancelStart

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(dot)albe(at)cybertec(dot)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
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