Hi,
I am using PL/SQL Developer version 11 on Windows 10 64bit and I keep getting the following error message:

"Initialization error
Could not initialize
C:\Oracle\product\instantclient_12_1\oci.dll

OCIDLL forced to C:\Oracle\product\instantclient_12_1\oci.dll
LoadLibrary(C:\Oracle\product\instantclient_12_1\oci.dll)
returned 0
"

. I have installed the following versions of the Oracle Client:
- Instant Client 11.3 (32bit)
- Instant Client 12.1 (32bit)
- Oracle client 11.2 (32bit)
I configure the IDE under tools/preferences to set the Oracle home and OCI library to point to the above client.
I also set the TNS_ADMiN environment variable.
All of the above to no avail. Please help.

Support Info below:

PL/SQL Developer
Version 11.0.4.1788 (64 bit)
02.100339 - 100 user license
Service Contract: 4/1/2016
Windows 10 Build 10586

Physical memory : 16,696,464 kB (13,123,296 available)
Paging file : 19,186,832 kB (15,484,372 available)
Virtual memory : 137,438,953,344 kB (137,438,645,220 available)

Parameters
C:\Program Files\PLSQL Developer\plsqldev.exe

Preferences
Session mode: Multi
OCI Library: C:\Oracle\product\instantclient_12_1\oci.dll
Use OCI7: False
Allow Multiple Connections: True

Preference Files
C:\Users\Roland\AppData\Roaming\PLSQL Developer\Preferences\default\Default.ini
C:\Users\Roland\AppData\Roaming\PLSQL Developer\Preferences\Roland\default.ini

License File
C:\Users\Roland\AppData\Roaming\PLSQL Developer\aalf.dat

Debug file
C:\Users\Roland\AppData\Roaming\PLSQL Developer\PlSqlDev.elf

Plug-Ins
*Active Query Builder (C:\Program Files\PLSQL Developer\PlugIns\ActiveQueryBuilder.dll)
*PL/SQL Documentation (plsqldoc) (C:\Program Files\PLSQL Developer\PlugIns\plsqldoc.dll)
*Red Gate Deployment Plug-In (C:\Program Files\PLSQL Developer\PlugIns\RedGate.dll)
(* is Active)

Aliases

Homes

DLLs
C:\Oracle\product\instantclient_12_1\oci.dll

TNS File

Using
Home:
DLL: C:\Oracle\product\instantclient_12_1\oci.dll
OCI: not initialized

Monitor
PixelsPerInch = 120

Id = 0
Primary = True
Handle = 65537
Left = 0
Top = 0
Width = 1920
Height = 1080

MainFormOnTaskbar = False

You may need to install the "Microsoft Visual C++ 2010 Redistributable Package (x86)":

http://www.microsoft.com/en-us/download/details.aspx?id=5555

This is apparently required for the Oracle Instant Client 12, but somehow not included.

Hi Marco,
Because I am using Windows 10, it seems like a newer version of the Visual C++ already exists... I get the following message when I try to install the 2010 version you listed above: "A newer version of Microsoft Visual C++ 2010 Redistributable has been detected on the machine."
Also, I get the OCI.dll error with all any/all of the Oracle Client versions installed on my computer. Please help.

Do you also get the error when you specify the Oracle Client via the "InstantClient" command-line parameter as described here?

Hi Worker,
Thank you for the suggestion. I modified the application shortcut as suggested here (http://www.allroundautomations.com/plsqldev110x64.html) and I get the same error when I use the 11 or 12 version of the Instant Client. Debug info below.



PL/SQL Developer
Version 11.0.4.1788 (64 bit)
02.100339 - 100 user license
Service Contract: 4/1/2016
Windows 10 Build 10586

Physical memory : 16,696,464 kB (10,599,256 available)
Paging file : 19,186,832 kB (11,453,744 available)
Virtual memory : 137,438,953,344 kB (137,438,641,432 available)

Parameters
C:\Program Files\PLSQL Developer\plsqldev.exe
InstantClient=C:\Oracle\product\instantclient_12_1

Preferences
Session mode: Multi
OCI Library:
Use OCI7: False
Allow Multiple Connections: True

Preference Files
C:\Users\Roland\AppData\Roaming\PLSQL Developer\Preferences\default\Default.ini
C:\Users\Roland\AppData\Roaming\PLSQL Developer\Preferences\Roland\default.ini

License File
C:\Users\Roland\AppData\Roaming\PLSQL Developer\aalf.dat

Debug file
C:\Users\Roland\AppData\Roaming\PLSQL Developer\PlSqlDev.elf

Plug-Ins
*Active Query Builder (C:\Program Files\PLSQL Developer\PlugIns\ActiveQueryBuilder.dll)
*PL/SQL Documentation (plsqldoc) (C:\Program Files\PLSQL Developer\PlugIns\plsqldoc.dll)
*Red Gate Deployment Plug-In (C:\Program Files\PLSQL Developer\PlugIns\RedGate.dll)
(* is Active)

Aliases

Homes

DLLs
C:\Oracle\product\instantclient_12_1\oci.dll

TNS File

Using
Home: <Instant Client>
DLL: C:\Oracle\product\instantclient_12_1\oci.dll
OCI: not initialized

Monitor
PixelsPerInch = 120

Id = 0
Primary = True
Handle = 65537
Left = 0
Top = 0
Width = 1920
Height = 1080

MainFormOnTaskbar = False

Do you have SQL*Plus installed in C:\Oracle\product\instantclient_12_1? If not, can you add it from the Instant Client download page?

If you have SQL*Plus available in C:\Oracle\product\instantclient_12_1, can you start it to verify that things are working correctly?

What if you add "C:\Oracle\product\instantclient_12_1" to PATH environment variable?
(If you have any Oracle Clients already in PATH, then make sure that this one is first in the PATH.)

Edit:
You may actually have to add two paths to PATH variable:

• C:\Oracle\product\instantclient_12_1
• C:\Oracle\product\instantclient_12_1\bin

When I use instantclient-basic-windows.x64-11.2.0.4.0.zip is OK.instantclient-basic-windows.x64-12.1.0.2.0.zip is Error.

Hi,
I have exactly the same environment as RNMVP "using PL/SQL Developer version 11 on Windows 10 64bit". And unfortunately, exactly the same error!!

P.S.: I connected to db by using SQL*Plus and specified the Oracle Client via the "InstantClient" command-line parameter. But issue still repeat.