I'm working with the Lead Service Lines Solutions package and have added the dltsolutions package to my cloned environment. I recently updated my Pro to version 3.0.1. Now, when I try to open even of the tools in the toolbox, I get the error:
Tool has failed to open.
Error HRESULT E_FAIL has been returned from a call to a COM component.
The package appears to be correctly installed with no updates available.
Same. I just upgraded from 2.8 to the latest version, which is 3.03. I haven't used the data loading toolbox before, but I just added it after the upgrade. Unable to use any of them, with the same error message you got.