Oracle ODAC / ODP 12c Uninstall

A few months ago when I reimaged my machine, I installed Oracle 12c with the latest ODP/ODAC.  It worked great, but only one pluggable database is supported for development.  I decided to uninstall and go back to 12g along with ODAC and ODP.  All worked smoothly, until I tried to connect to Oracle database. Then I got an error that data provider for entity framework could not be loaded – – “Failed to find or load the registered .Net Framework Data Provider”.  I double-checked machine.config, both 32 and 64 bit versions.  I checked GAC, and it looked OK there as well.  I actually uninstalled everything from GAC and re-installed Oracle.DataAccess.dll for both 32 and 64 bit versions.  Still, the same error!!! I spent literally 5 hours, trying different things, and I could not see what I was doing wrong.  Finally when I copied the Oracle.DataAccess.dll  into bin folder, I got somewhat descriptive error that Oracle.DataAccess.dll  for version 1.121 could not be loaded.  I checked, and 12g release 5 of ODAC is version 4.112.  Version 4.121 is the release for 12c.  Why is .NET trying to load that?

Finally, I performed file search from Visual Studio in, and what do you know, I found a config file that 12c installer put in with binding redirect to version 4.121!  I was so mad.  Why on earth would Oracle installer do this?

I hope this helps another poor soul.



  1. I have not yet installed the latest 12c ODAC but it looks like we might need to in order to use the Entity Framework designer and use the Server view in Visual Studio 2013. If I try to add an Oracle connection in VS2013 with the current ODAC installed, evidently VS2013 sees some other deprecated version and I have no option to choose a schema. Now that I’ve seen this blog, I don’t think I’ll install the ODAC 12c on my box unless I set up a VB. Thanks.

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