&tldr; in sqlnet.ora :
# the minimum allowed client version to connect to the databases from this home
# set this to accept lower versions of the autentication protocol
# if you have a database link to a lower version of an Oracle
# set this to that lower version to talk the same authentication protocol
# 12a => 126.96.36.199
# 12a for Oracle Database 12c release 188.8.131.52 or later
# 12 for the critical patch updates CPUOct2012 and later Oracle Database 11g
# 11 for Oracle Database 11g
# 10 for Oracle Database 10g
# 9 for Oracle9i
# 8 for Oracle8i
Ah, an old client is trying to connect to Oracle 12c (presumably)… ;)
Also “ORA-03134: Connections to this server version are no longer supported” can occur.
This actually implies that the authentication protocols use between client and server do not match. In Oracle 12c, the authentication protocol uses SHA-2 encryption algorithm by default, where older clients use SHA-1. So when an older client is used with defaults, the server will not accept the connection.
The best option would be upgrading the client, but when older dll’s are used (like ojdbc14.jar and you can not change this), this is a problem. The database instance can be told to accept older clients and use the older SHA-1 encryption algorithm.
Connecting with the Oracle Instant Client 11g to Amazon Cloud Web Services (amazonaws.com) can result in the next error:
ORA-28547: connection to server failed, probable Oracle Net admin error
I found that while pinging the host, it was not able to resolve it, but connecting with SQL Developer (184.108.40.206) was possible! Strange…
I downloaded the Oracle Instant Client 12c (220.127.116.11) and that works. It seems the Oracle Instant Client 11g (18.104.22.168) is not able to connect to Amazon Web Services…
— Checked for relevance on Januari 21, 2017
The Oracle Database version compatibility matrix and version support status matrix are almost mandatory when installing or upgrading clients or servers.
Oracle Database client / server version compatibility matrix
Oracle calls this Client / Server Interoperability Support, Note ID 207303.1
Oracle Database version release support status matrix
Oracle calls this the Database Releases Support Status Summary, Note ID 161818.1
You will be redirected to Oracle Support and you must be registered to gain access to the pages. I did not include the matrices, because these change over time.
Oracle Information about Windows 32 / 64 bit database and client versions
Certification Information for Oracle Database on Microsoft Windows x64 (64-bit), Doc ID 1307195.1
Installing the Oracle Instant Client will save you ~600 megabyes compared to the ‘full’ Oracle Client.
- Download Basic Package from the Oracle site
- Unzip to directory x (your ORACLE_HOME)
- Set PATH (Windows) or LD_LIBRARY_PATH (*nix) to the Instant Client directory x
- Move TNSNAMES.ora to directory x/network/admin (or set TNS_ADMIN and ORACLE_HOME).
- Extend with SQL*Plus Package (optional)
- Start your application
Read my full article here: Whiteblog – Installing the Oracle Instant Client. (links in referred blog might not work!)
OLE DB, .NET and ASP.NET drivers are not included in the instant client (first Oracle link might suggest it is). These are included in the ODAC package, download them separately at these locations:
Instant Client vs Full Client (Administrator and Runtime)
What Are The Different Oracle Client Components Installed With Different Installation Types (too much to sum up):
Client master note
Master Note For Oracle Database Client Installation (Doc ID 1157463.1)
Checked for relevance on November 4th, 2019.