--- On Wed, 12/11/08, Tony Fernandez <Tony.Fernandez at vocalocity.com> wrote:

> Date: Wednesday, 12 November, 2008, 10:52 PM
> Hello lists,
> 
>  
> 
> I am trying to run Slony on a Master Postgres 8.1.11
> replicating to a
> Slave same version and 2nd Slave Postgres 8.3.4.

> 
> I am getting the following error:
> 
>  
> 
> <stdin>:14: PGRES_FATAL_ERROR load
> '$libdir/xxid';  - ERROR:
> incompatible library "/usr/lib/pgsql/xxid.so":
> missing magic block
> 
> HINT:  Extension libraries are required to use the
> PG_MODULE_MAGIC
> macro.
> 
> <stdin>:14: Error: the extension for the xxid data
> type cannot be loaded
> in database 'dbname=hdap host=10.0.100.234 port=6543
> user=myuser
> password=mp'

I think you've proabably built slony against one version of postgres and then tried to use it with another. You must build against 8.1.11 and then separately for 8.3.4, using the same version of slony ofcourse.