Dear community, Michael and Antonio.
Thanks for your comments, they are very usefull.
We found another issue, it was the bytea_output variable, to migrate a database from postgres 8.4 to postgres 9.3 is necesary to set the bytea_output variable to "scape". The lob_data table does not work with bytea_output hex (default value in this variable). http://www.postgresql.org/docs/9.3/static/runtime-config-client.html#GUC-BYTEA-OUTPUT
So, now we are working with openACS 5.5, .LRN 2.5 and postgresql 9.3
Thanks again.
All the best,