Q:

Error: 21626, while configuring Oracle publication

We are facing "Microsoft SQL Server, Error: 21626" while configuring oracle publication in SQL server 2008.
Any help is highly appreciated.

A:

As mentioned in Troubleshooting Oracle Publishers, error 21626 is raised when the SQL Server Distributor cannot connect to the Oracle Publisher and the following error message is shown:
Unable to connect to Oracle database server '%s' using the Oracle OLEDB provider OraOLEDB.Oracle.
Verify connectivity to the Oracle database using SQL*PLUS, using the same login and password specified when you configured the Oracle Publisher.
In addition, as stated in the section The SQL Server Distributor Cannot Connect to the Oracle Database Instance, ensure the following:

The necessary Oracle software is installed on the Distributor.
The Oracle database is online and you can connect to it using a tool
like SQL*Plus.
The login replication uses to connect to the Oracle Publisher has
sufficient permissions. For more information, see Configure an Oracle
Publisher.
The TNS names defined during configuration of the Oracle Publisher
are listed in the tnsnames.ora file.
The correct Oracle Home and path are used. Even if you have only one
set of Oracle binaries installed on the SQL Server Distributor,
ensure that the environment variables related to the Oracle Home are
set properly. If you change environment variable values, you must
stop and restart SQL Server for the change to take effect.

