I had a Windows Server 2003 and I was trying to connect to Oracle with the System.Data.OracleClient provider.
I was able to connect from a console application but not from ASP.NET.
From ASP.NET I only got ORA-12154 errors.
I found that on Windows 2003 Server, ASP.NET applications run in the
security context of the “Network Service” user.
So I tried these two things:
I first started following these steps:
1. Log on to Windows as a user with Administrator privileges.
2. Launch Windows Explorer from the Start Menu and and navigate to the
ORACLE_HOME folder. It is usually under the oracle instalation folder.
In my case that is C:\oracle\product\10.2.0\client_1
3. Right-click on the ORACLE_HOME folder and choose the "Properties" option
from the drop down list. A "Properties" window should appear.
4. Click on the "Security" tab of the "Properties" window.
5. Click on "Authenticated Users" item in the "Name" list (on Windows XP
the "Name" list is called "Group or user names").
6. Uncheck the "Read and Execute" box in the "Permissions" list under the
"Allow" column (on Windows XP the "Permissions" list is called
"Permissions for Authenticated Users").
7. Re-check the "Read and Execute" box under the "Allow" column (this is
the box you just unchecked).
8. Click the "Advanced" button and in the "Permission Entries" list make
sure you see the "Authenticated Users" listed there with:
Permission = Read & Execute
Apply To = This folder, subfolders and files
If this is NOT the case, edit that line and make sure the "Apply onto"
drop-down box is set to "This folder, subfolders and files". This
should already be set properly but it is important that you verify this.
9. Click the "Ok" button until you close out all of the security properties
windows. The cursor may present the hour glass for a few seconds as it
applies the permissions you just changed to all subfolders and files.
10. Reboot your computer to assure that these changes have taken effect.
(I thought that rebooting was not that important but it seems that you have to reboot to make changes effective)
It sometimes happens that it is not enough, because it seems that some oracle installations need the
the ASP.NET process to run with an account with sufficient privileges.
The second thing you can do in that case is.
1. First open the machine.config file. That will be usually in %windir%\Microsoft.NET\Framework\v2.0.50727\CONFIG\machine.config
2. Look for something like:
<system.web>
<processModel autoConfig="true" />
3. Add the userName=”System” attribute. For example
<processModel autoConfig="true" userName="System" />
4. Restart the IIS.