"Unable to determine the source location for some packages" for specific packages

Is this log with htmlwidgets installed from Github? Because the idea is to have htmlwidgets installed from the Posit Package Manager before the GitHub packages start to be compiled and it is not getting installed at all.

Can you make sure you have htmlwidgets installed from CRAN in your system (delete and reinstall if you can just to be dead sure), try to deploy again and post the deployment log again? BTW please post the console output as formatted code it makes things far easier to read. Here is how to do it: