Ok, when you know for sure other applications that used the same process worked; on your new application make sure you have the data access reference and the three dll files...
I downloaded ODAC1120320Xcopy_32bit this from the Oracle site:
http://www.oracle.com/technetwork/database/windows/downloads/utilsoft-087491.html
Reference: Oracle.DataAccess.dll (ODAC1120320Xcopy_32bit\odp.net4\odp.net\bin\4\Oracle.DataAccess.dll)
Include these 3 files within your project:
When I tried to create another application with the correct reference and files I would receive that error message.
The fix: Highlighted all three of the files and selected "Copy To Output" = Copy if newer. I did copy if newer since one of the dll's is above 100MB and any updates I do will not copy those files again.
I also ran into a registry error, this fixed it.
public void updateRegistryForOracleNLS()
{
RegistryKey oracle = Registry.LocalMachine.CreateSubKey(@"SOFTWARE\ORACLE");
oracle.SetValue("NLS_LANG", "AMERICAN_AMERICA.WE8MSWIN1252");
}
For the Oracle nls_lang list, see this site: https://docs.oracle.com/html/B13804_02/gblsupp.htm
After that, everything worked smooth.
I hope it helps.