I'm attempting to install SQL Server Data Tools, but the installation is hanging. It had an error the first attempt; and I've restarted the machine (as that seems to help in those scenarios). Now it just sits there on the tools for Visual Studio not installing (I've left it running over night). Any suggestions on what to do here?
I experienced exactly the same error, right down to the pixel. I figured out the solution by continuing the broken installation using the standard VS 2017 installer (it will recognize that the SSDT installer error'd out). Resuming this installer reported more information via error logs. The errors were folder/file access permissions being restricted by McAfee Anti-virus
tldr; disable your anti-virus.
Make sure windows update service isn't running via task manager. I have had that stall these installs many times.
Also if you uninstall McAfee via control panel still gives this installation issue, you have to download from McAfee website the MCPR (McAfee Removal Tool), run it and then after restart you will be able to Install SSDT 2017 without any problem.