Previously I have been able to add, delete, and re-create datasources for the gateway via the 'Manage' Gateways' menu in the Power BI Service, but no longer.
When trying to add a new datasource, I get the following error message;
I have installed the latest gateway version, which seems to be working properly
Looking at the gateway logs, there are messages about TLS and the framework version. I have uninstalled the .NET framework, and reinstalled version 4.0, 4.5, and 4.6 in succession, but the error messages remain.
Have you instlled the Teradata connector on your device? You could have a reference of the similar threads bleow which have been solved.
In addition, if you still have this issue, I suggest you could create a ticket in Power BI Support.(If you have Power BI Pro)