ORA-12638: Credential retrieval failed - oracle

Question

I have a legacy VB6 application which I've inherited. The issue I'm facing is that I'm getting the infamous
ORA-12638: Credential retrieval failed
error message whenever it tries to connect to one of our Oracle databases. I can connect fine from SQLPlus and Toad, however. I've Googled around and everyone seems to say that modifying their sqlnet.ora file to
SQLNET.AUTHENTICATION_SERVICES=(NONE)
did the trick. I have yet to find anyone with an alternative fix. Here is what my connection string looks like:
"PROVIDER=OraOLEDB.Oracle;DATA SOURCE=(DESCRIPTION = " & _
"(ADDRESS = (PROTOCOL = TCP)(HOST = server1)
(PORT = 1521))" & _
"(ADDRESS = (PROTOCOL = TCP)(HOST = server2)
(PORT = 1521))" & _
"(LOAD_BALANCE = yes) " & _
"(CONNECT_DATA = " & _
"(SERVER = DEDICATED) " & _
"(SERVICE_NAME = database_name_here) " & _
") " & _
"); " & _
"User Id=username_here;Password=password_here;"
As for my VB code, it's quite simple.
Private oracleDatabaseConnection As ADODB.Connection
Set oracleDatabaseConnection = New ADODB.Connection
oracleDatabaseConnection.Open oracleConnectionString
Anyone have any ideas?
Thank you. :)

Answer 1

I know this is a very old post but I have found a solution that has worked for me (Legacy VB6 Application):
Change the following entry in the sqlnet.ora file:
Original Entry - SQLNET.AUTHENTICATION_SERVICES= (NTS)
Modified Entry - SQLNET.AUTHENTICATION_SERVICES= (NONE)
Here is a LINK to the solution

Answer 2

Honestly this is one of those errors that can be caused by lots of different root problems.
On the assumption your database server is Windows, check its event log, both System and Application. You may find something there that is useful.
I have encountered this error in some cases because the account under which the Oracle service was running got locked.
I have also encountered it in cases where we never found the explanation, but we were always able to clear up the issue by having the user lock and unlock their PC.
Is the VB application running on a different machine than the client that can connect? If so, is it possible to test using a different client program on the same machine -- or is it possible to try the VB application on your machine?

Answer 3

Know it's an old question but it has started appearing with the recent Windows update.
The way to easily solve it is to set
SQLNET.AUTHENTICATION_SERVICES= (NONE)
in the sqlnet.ora.

Answer 4

If you are running a web app under IIS, restarting IIS seem to help. But this is one sucker of an issue that has not much reasoning behind.

Answer 5

I installed Oracle Database 11g Express Edition 32-bit on Windows 10 professional 64-bit (spanish edition).
After restart PC all works ok.
But the next day I get error using SQL*PLus and SQLTools 1.9 build 15:
ORA-12638: Credential retrieval failed
I modified the sqlnet.ora file so:
SQLNET.AUTHENTICATION_SERVICES= (NONE)
and now I can connect using SQLPlus, SQLTools 1.9 build 15.

Answer 6

If using IIS and for a VB app, it may help to create a new Data Source in the ODBC manager and referencing it by name (instead of by provider) in the connection string.
For example, if the name for the Data Source is "test_ds", I would replace
ObjConn.open "Provider=MSDAORA;User ID=myuser;password=mypassword;Data Source=MYDATASOURCEFROMTNSNAMES;Persist Security Info=False"
for
ObjConn.open "dsn=test_ds;pwd=mypassword"
Can't really explain the logic behind the solution, but it worked for me.

Answer 7

Note also that Windows client connections can fail with this error, when using Windows Hello login.
Whatever windows authentication for a connect like:
sqlplus un/pw#Dev
failed with ora-12638, when I logged into my laptop with Face recognition (ie. using Hello)
To get around this, either set SQLNET.AUTHENTICATION_SERVICES = (NONE)
or just login with your tradition windows username and password.