Hi @SANDEEP TADISHETTY ,
Please first make sure that you target server version is SQL Server2019.
When using TNS service name in tnsnames.ora, user may encounter this error if the environment is not set right. There are few ways to fix:
1.Add TNS_ADMIN to system environment variable, which value is the path of tnsnames.ora file.
2.Set OracleHome and OracleHome64 in Oracle connection manager to tnsnames.ora path in x86 and x64 Oracle client respectively.
3.Use format [//]host[:port][/service_name] in the TNS service name field in connection manager to connect instead.
Reference: Microsoft Connector for Oracle is released for SQL Server 2019 Preview
Regards,
Zoe Hui
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