Here are common resolutions for this error message:
1. Make sure there is only a single version of ODP.NET on the machine.
2. Also, you might need to modify the machine.config file located at C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\ to reflect the latest ODAC version that exists on the system.
- For example, update the version numbers on the lines similar to:
<add name="Oracle Data Provider for .NET" invariant="Oracle.DataAccess.Client" description="Oracle Data Provider for .NET" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=126.96.36.199, Culture=neutral, PublicKeyToken=89b483f429c47342" />
3. Uninstall your existing ODP.NET installation in case it is corrupted. Then install a new version.
4. If the 64-bit ODP.NET file was missing, you will need to add this, and then you will be able to start the TDoD service.