Format request failed, no matching language servers.

[wookayin]

When requesting LSP formatting on a markdown file (where null-ls LSP client is attached), the following information/warning message pops up:

[LSP] Format request failed, no matching language servers.

I am invoking LSP format request via BufWritePost autocmd (which works for other filetypes such as python and javascript for auto-formatting):

vim.lsp.buf.format({timeout_ms = 1000})

For the markdown file, I have the null-ls LSP client attached:

1 client(s) attached to this buffer:                                                                                                                             
                                                                                                                                                                 
Client: null-ls (id: 2, pid: 5001, bufnr: [1, 102, 138])                                                                                                         
 filetypes:       python, javascript, graphql, css, handlebars, markdown, typescript, yaml, vue, html, typescriptreact, jsonc, less, json, javascriptreact, scss 
 autostart:       false                                                                                                                                          
 root directory:  ...                                
 cmd:             nvim                                                                                                                                           

whose server_capabilities is like:

{
    codeActionProvider = {
        resolveProvider = false
    },
    completionProvider = {
        allCommitCharacters = {
        },
        completionItem = {
            labelDetailsSupport = true

        },
        resolveProvider = false,
        triggerCharacters = {
            ".",
            ":",
            "-"
        }
    },
    documentFormattingProvider = true,
    documentRangeFormattingProvider = true,
    executeCommandProvider = true,
    hoverProvider = true,
    textDocumentSync = {
        change = 1,
        openClose = true,
        save = {
            includeText = true
        }
    }
}

My null-ls config (simplified):

  local _cond = function(cmd, source)
    if vim.fn.executable(cmd) > 0 then return source
    else return nil end
  end

  null_ls.setup({
    sources = _exclude_nil {
      -- [[ Auto-Formatting ]]
      -- @python (pip install yapf isort)
      _cond("yapf", null_ls.builtins.formatting.yapf),
      _cond("isort", null_ls.builtins.formatting.isort),
      -- @javascript
      null_ls.builtins.formatting.prettier,

      -- Linting (diagnostics)
      -- @python: pylint, flake8
      _cond("pylint", null_ls.builtins.diagnostics.pylint.with({
        method = null_ls.methods.DIAGNOSTICS_ON_SAVE,
        condition = ...,
      })),
      _cond("flake8", null_ls.builtins.diagnostics.flake8.with({
        method = null_ls.methods.DIAGNOSTICS_ON_SAVE,
        -- Activate when flake8 is available and any project config is found,
        -- per https://flake8.pycqa.org/en/latest/user/configuration.html
        condition = ...,
        -- Override flake8 diagnostics levels
        -- @see https://github.com/jose-elias-alvarez/null-ls.nvim/issues/538
        on_output = ...,
    },

    -- Debug mode: Use :NullLsLog for viewing log files (~/.cache/nvim/null-ls.log)
    debug = false,
  })

It looks like the prettier module is responsible for formatting markdown.

My question is:

• Why am I getting such errors? In previous versions of neovim/null-ls.vim, it worked fine on markdown files.
• How can I suppress the error? Or shouldn't I do that, if it is a configuration miss?

[wookayin]

It looks like it's my bad, in order for null_ls.builtins.formatting.prettier to work the prettier program should be available in the command line. Installing npm i -g prettier resolves the error.

The error message was a bit confusing; do you see any room for improving the error message when the underlying formatter fails for some reason? I believe the error message should be something like null-ls or an underlying source (prettier) has failed, reason: command not found, rather than "no matching language servers".

[jose-elias-alvarez]

Definitely agree that we can improve this. In most cases, null-ls will show a warning, but for sources like prettier that have extra logic to attempt to find local executables in node_modules, we don't show anything, which can lead to confusion.

#892 is an attempt to fix this (and my comment there describes potential pitfalls with the solution).

[wwweww]

I get a value of 1 after executing the command:echo executable("autopep8") but I have the same problem with autopep8