Installing Oracle 32-bit Client on Windows Server Already Running 64-bit Oracle Database Server

Here is an instruction how to install 32-bit and 64-bit Oracle Client on one machine. Follow the instruction, then it should work.

Assumptions: Oracle Home is called OraClient11g_home1, Client Version is 11gR2

• Download and install Oracle x86 Client, for example into C:\Oracle\11.2\Client_x86

• Download and install Oracle x64 Client into different folder, for example to C:\Oracle\11.2\Client_x64

• Open command line tool, go to folder %WINDIR%\System32, typically C:\Windows\System32 and create a symbolic link ora112 to folder C:\Oracle\11.2\Client_x64 (see commands section below)

• Change to folder %WINDIR%\SysWOW64, typically C:\Windows\SysWOW64 and create a symbolic link ora112 to folder C:\Oracle\11.2\Client_x86, (see below)

• Modify the PATH environment variable, replace all entries like C:\Oracle\11.2\Client_x86 and C:\Oracle\11.2\Client_x64 by C:\Windows\System32\ora112, respective their \bin subfolder. Note: C:\Windows\SysWOW64\ora112 must not be in PATH environment.

• If needed set your ORACLE_HOME environment variable to C:\Windows\System32\ora112

• Open your Registry Editor. Set Registry value HKLM\Software\ORACLE\KEY_OraClient11g_home1\ORACLE_HOME to C:\Windows\System32\ora112. Using C:\Oracle\11.2\Client_x64 should also work.

• Set Registry value HKLM\Software\Wow6432Node\ORACLE\KEY_OraClient11g_home1\ORACLE_HOME to C:\Windows\System32\ora112 (not C:\Windows\SysWOW64\ora112). Using C:\Oracle\11.2\Client_x86 should also work.

• You are done! Now you can use x86 and x64 Oracle client seamless together, i.e. an x86 application will load the x86 libraries, an x64 application loads the x64 libraries without any further modification on your system.

• Probably it is a smart idea to set your TNS_ADMIN environment variable (resp. TNS_ADMIN entries in Registry) to a common location, for example TNS_ADMIN=C:\Oracle\Common\network\admin

Commands to create symbolic links:

cd C:\Windows\System32 mklink /d ora112 C:\Oracle\11.2\Client_x64 cd C:\Windows\SysWOW64 mklink /d ora112 C:\Oracle\11.2\Client_x86

Notes:

Both symbolic links must have the same name, e.g. ora112.

Despite of their names folder C:\Windows\System32 contains the x64 libraries, whereas C:\Windows\SysWOW64 contains the x86 (32-bit) libraries. Don't get confused.

I had the same issue. Both 32 and 64 bit ORA clients installed on same Windows 10 machine (separate folders) and 32 bit apps stopped working. All I had to do was edit the System Environment variables and DELETE the ORACLE_HOME entry, then re-boot. Windows/Oracle do the rest based on the registry entries. Just need to copy the tnsnames.ora to both installations.