Troubleshooting

Automatic setup failed

To figure out what happened use the function require('lsp-zero.check').run() in command mode, pass a string with the name of the language server.

Here is an example with lua_ls.

:lua require('lsp-zero.check').run('lua_ls')

Note:

The name of the language server must match with one in this list: server_configurations.

If the language server is not being configured you'll get a message like this.

LSP server: lua_ls
- was not installed with mason.nvim
- hasn't been configured with lspconfig

This means mason.nvim doesn't have the server listed as "available" and that's why the automatic setup failed. Try re-install with the command :LspInstall.

When everything is fine the report should be this.

LSP server: lua_ls
+ was installed with mason.nvim
+ was configured using lspconfig
+ "lua-language-server" is executable

If it says - "lua-language-server" was not found it means Neovim could not find the executable in the "PATH".

You can inspect your PATH using this command.

:lua vim.tbl_map(print, vim.split(vim.env.PATH, ':'))

Note:

If you use windows replace ':' with ';' in the second argument of vim.split.

The executable for your language server should be in one of those folders. Make sure it is present and the file itself is executable.

Root directory not found

You used the command :LspInfo and it showed root directory: Not found. This means nvim-lspconfig couldn't figure out what is the "root" folder of your project. In this case you should go to lspconfig's github repo and browse the server_configurations file, look for the language server then search for root_dir, it'll have something like this.

root_pattern("somefile.json", ".somefile" , ".git")

root_pattern is a function inside lspconfig, it tries to look for one of those files/folders in the current folder or any of the parent folders. Make sure you have at least one of the files/folders listed in the arguments of the function.

Now, sometimes the documentation in lspconfig just says see source file. This means you need to go the source code to figure out what lspconfig looks for. You need to go to the server config folder, click in the file for the language server, look for the root_dir property that is inside a "lua table" called default_config.

Inspect server settings

Let say that you added some "settings" to a server... something like this.

lsp.configure('tsserver', {
  settings = {
    completions = {
      completeFunctionCalls = true
    }
  }
})

Notice here that we have a property called settings, and you want to know if lsp-zero did send your config to the active language server. Use the function require('lsp-zero.check').inspect_settings() in command mode, pass a string with the name of the language server.

:lua require('lsp-zero.check').inspect_settings('tsserver')

If everything went well you should get every default config lspconfig added plus your own.

If this didn't showed your settings, make sure you don't call lspconfig in another part of your neovim config. lspconfig can override everything lsp-zero does.

Inspect the entire server config

Use the function require('lsp-zero.check').inspect_server_config() in command mode, pass a string with the name of the language server.

Here is an example.

:lua require('lsp-zero.check').inspect_server_config('tsserver')

Note:

The name of the language server must match with one in this list: server_configurations.

Testing a server in isolation

And by that I mean without the lsp-zero setup.

First thing you'll need to do is delete or "comment out" the configuration you have for lsp-zero. Then do everything manually. Call the setup function for mason and mason-lspconfig. After that, use lspconfig to configure the language server you want to test. If you use lsp-zero's keybindings or commands, you can add them in the .on_attach function.

Here is an example configuration for tsserver.

local lsp_zero = require('lsp-zero')
local lspconfig = require('lspconfig')

require('mason').setup()
require('mason-lspconfig').setup()

lspconfig.tsserver.setup({
  capabilities = require('cmp_nvim_lsp').default_capabilities(),
  on_attach = function(client, bufnr)
    lsp_zero.default_keymaps({buffer = bufnr})
    lsp_zero.buffer_commands()
  end
})

If the issue you have persists even without lsp-zero and you want to ask for help in stackoverflow or any other forum, I suggest you present a minimal config like this one. You'll increase the chances of getting support from the community (because sadly there aren't any lsp-zero experts out there).

If you need a minimal config for nvim-cmp, use this.

local cmp = require('cmp')

cmp.setup({
  sources = {
    {name = 'nvim_lsp'},
  },
  snippet = {
    expand = function(args)
      require('luasnip').lsp_expand(args.body)
    end,
  },
  mapping = cmp.mapping.preset.insert({
    ['<C-Space>'] = cmp.mapping.complete(),
    ['<C-b>'] = cmp.mapping.scroll_docs(-4),
    ['<C-f>'] = cmp.mapping.scroll_docs(4),
  })
})