When trying to connect to the database, the following error appears: 'Error message: NET: IOHandler is not specified'
If you have an Oracle client, or instant client on your machine, please ensure the following steps are taken:
1. In Windows, go to the Environment Variables list, and in the 'System Variables' section, add the path of the folder where the oci.dll file is, e.g. C:\instantclient_23_6\ (Please add this so it is first in the list)
2. Open Toad and in the connection window, tick the 'Connect using Oracle Client' box and try the connection from Toad again.