When I add a code-first EF migration, I get the following error:
Field not found: 'OracleInternal.Common.ODTSettings.m_bUseLongIdentifiers'.
and the migration is not created.
I'm targeting Oracle 12c and verified my connection strings and all the configuration. The same configuration works perfectly in another project.
Apparently the latest stable ODP.net drivers has a bug, you need to down grade your ODP.net drivers to the previous stable version.
Try the following packages;
Install-Package Oracle.ManagedDataAccess -Version 12.1.22
Install-Package Oracle.ManagedDataAccess.EntityFramework -Version 12.1.22