Linux Mint, LazyVim, Mason, Conform, CSharpier and dotnet

2025, July 31st

Almost two full weeks after moving from Windows 10 to Linux Mint.

I’ve been coding in .NET 8 without major problems besides being unable to use a LSP (maybe I’ll write some other post¹ if I ever find out why).

But working without a formatter has been a pain point too, so I decided to figure out why CSharpier (installed with Mason) was not working.

Turns out, LazyVim uses Conform to do the formatting and it defaults to using LSP formatting unless it is configured for a file type.

Knowing that, I wrote a first configuration override in ~/.config/nvim/lua/plugins/conform.lua:

return {
  "stevearc/conform.nvim",
  opts = {
    formatters_by_ft = {
      cs = { "csharpier" },
    },
  },
}

That fixed the problem of the formatter not being called but revealed another: it was always throwing an error when saving.

Formatter 'csharpier' error: Could not execute because the specified command or file was not found.
Possible reasons for this include:
* You misspelled a built-in dotnet command.
* You intended to execute a .NET program, but dotnet-csharpier does not exist.
* You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.

Looking at the default Conform configuration (found in ~/.local/share/nvim/lazy/conform.nvim/lua/conform/formatters), CSharpier has this:

---@type conform.FileFormatterConfig
return {
  meta = {
    url = "https://github.com/belav/csharpier",
    description = "The opinionated C# code formatter.",
  },
  command = "dotnet",
  args = { "csharpier", "--write-stdout" },
  stdin = true,
}

Comparing the above with the CSharpier documentation it is clear that the format command is missing. So I added a few more lines to my configuration:

return {
  "stevearc/conform.nvim",
  opts = {
    formatters = {
      csharpier = {
        command = "dotnet",
        args = { "csharpier", "format", "--write-stdout" },
        stdin = true,
      },
    },
    formatters_by_ft = {
      cs = { "csharpier" },
    },
  },
}

Even after that it still was failing with the same error so I ended up installing CSharpier globally (by running dotnet tool install csharpier --global in a terminal) and changing the configuration again so that the command is now csharpier instead of dotnet:

return {
  "stevearc/conform.nvim",
  opts = {
    formatters = {
      csharpier = {
        command = "csharpier",
        args = { "format", "--write-stdout" },
        stdin = true,
      },
    },
    formatters_by_ft = {
      cs = { "csharpier" },
    },
  },
}

And with all that I have an auto-formatter working even without a LSP.