ORA-01017: invalid username/password; logon denied when updating WebLogic data source and you know the username and password are correct

Background

The title might sound a bit confusing, because everyone that has experienced an ORA-01017 knows it only happens if either the database username or password is incorrect.

I recently had to change the password for all of the infrastructure component schemas in a Oracle® SOA Suite 12.1.3 installation. How to do it is documented at https://docs.oracle.com/middleware/1213/core/ASADM/repos.htm#ASADM637

After running the modifyBootStrapCredential for the OPSS configuration I expected everything to be dandy except a few ORA-01017 errors for the data sources I had not yet updated with the new password. Everything I needed to do was to edit each data source and provide the new password. Or so I thought...

The problem

When I tried to apply the changes I got the following ORA-01017 error for each data source I tried to edit:

I was a bit thunderstruck at first because the username and passwords worked fine in both SQL*Plus and in SQL Developer.

The AdminServer out file contained errors like this:
<Jan 19, 2016 1:15:54 PM UTC> <Error> <Deployer> <BEA-149205> <Failed to initialize the application "LocalSvcTblDataSource" due to error weblogic.application.ModuleException: weblogic.common.resourcepool.ResourceSystemException:
 Could not create connection for datasource '<data source name>'.

 The returned message is: ORA-01017: invalid username/password; logon denied

 It is likely that the login or password is not valid.
 It is also possible that something else is invalid in
 the configuration or that the database is not available.
weblogic.application.ModuleException: weblogic.common.resourcepool.ResourceSystemException:
 Could not create connection for datasource '<data source name>'.

 The returned message is: ORA-01017: invalid username/password; logon denied

 It is likely that the login or password is not valid.
 It is also possible that something else is invalid in
 the configuration or that the database is not available.
        at weblogic.jdbc.module.JDBCModule.prepare(JDBCModule.java:350)
        at weblogic.application.internal.flow.ModuleListenerInvoker.prepare(ModuleListenerInvoker.java:100)
        at weblogic.application.internal.flow.ModuleStateDriver$1.next(ModuleStateDriver.java:175)
        at weblogic.application.internal.flow.ModuleStateDriver$1.next(ModuleStateDriver.java:170)
        at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:42)
        Truncated. see log file for complete stacktrace
Caused By: weblogic.common.resourcepool.ResourceSystemException:
 Could not create connection for datasource '<data source name>'.

 The returned message is: ORA-01017: invalid username/password; logon denied

 It is likely that the login or password is not valid.
 It is also possible that something else is invalid in
 the configuration or that the database is not available.
        at weblogic.jdbc.common.internal.JDBCUtil.parseException(JDBCUtil.java:322)
        at weblogic.jdbc.common.internal.ConnectionEnvFactory.makeConnection0(ConnectionEnvFactory.java:492)
        at weblogic.jdbc.common.internal.ConnectionEnvFactory.access$000(ConnectionEnvFactory.java:20)
        at weblogic.jdbc.common.internal.ConnectionEnvFactory$1.run(ConnectionEnvFactory.java:388)
        at java.security.AccessController.doPrivileged(Native Method)
        Truncated. see log file for complete stacktrace
>

The workaround

For each data source I had to do the following to work around this problem:

1. Clicked the Lock & Edit button.
2. Had to note which targets the data source was using.
3. Removed the targets from the data source, and clicked on the Save button.
4. Clicked on the Activate Changes button.
5. Clicked the Lock & Edit button.
6. Updated the password for the data source, and clicked on the Save button.
7. Clicked on the Activate Changes button.
8. Clicked the Lock & Edit button.
9. Added the targets that I noted in step 2 to the data source, before I clicked on the Save button.
10. Clicked the Activate Changes button.

After all data sources had been updated with the new passwords, and the data sources had been re-targeted, I did a full domain restart. 

While I started the AdminServer up, I looked out for errors like these which could indicate I had forgotten to update some data sources:

<Jan 19, 2016 1:32:34 PM UTC> <Error> <Deployer> <BEA-149205> <Failed to initialize the application "<data source name>" due to error weblogic.application.ModuleException: weblogic.common.resourcepool.ResourceSystemException