@jel111 As some additional information.
Checking the Build configuration documentation you’ll see that Base directory has this explanation:
- Base directory: directory where Netlify checks for dependency management files such as
package.jsonor.nvmrc, installs dependencies, and runs your build command. The build system will use this directory to perform caching during the build process. If not set, the base directory defaults to the root of the repository.
You’ve input the name of your repository branch into a field intended for a directory.
As @dig has outlined, (and the documentation quoted mentions), you don’t need to specify a Base directory if it’s the root of your repository.