How to Keep Syntax Color but Disable Highlighting in Vim?

Question

I recently activated auto-complete using YouCompleteMe and syntax color in Vim. However, a red highlighting color appeared.

I tried to disable syntax color with syntax off, but this highlighting color is still there.

Here's my ~/.vimrc

    syntax on
    
    set nocompatible             " be iMproved, required
    filetype on                  " required
    
    " set the runtime path to include Vundle and initialize
    set rtp+=~/.vim/bundle/Vundle.vim
    call vundle#begin()
    " alternatively, pass a path where Vundle should install plugins
    "call vundle#begin('~/some/path/here')
    
    " let Vundle manage Vundle, required
    Plugin 'VundleVim/Vundle.vim'
    Plugin 'ycm-core/YouCompleteMe'
    
    " The following are examples of different formats supported.
    " Keep Plugin commands between vundle#begin/end.
    " plugin on GitHub repo
    Plugin 'tpope/vim-fugitive'
    " plugin from http://vim-scripts.org/vim/scripts.html
    " Plugin 'L9'
    " Git plugin not hosted on GitHub
    Plugin 'git://git.wincent.com/command-t.git'
    " git repos on your local machine (i.e. when working on your own plugin)
    Plugin 'file:///home/gmarik/path/to/plugin'
    " The sparkup vim script is in a subdirectory of this repo called vim.
    " Pass the path to set the runtimepath properly.
    Plugin 'rstacruz/sparkup', {'rtp': 'vim/'}
    " Install L9 and avoid a Naming conflict if you've already installed a
    " different version somewhere else.
    " Plugin 'ascenator/L9', {'name': 'newL9'}
    
    " All of your Plugins must be added before the following line
    call vundle#end()            " required
    filetype plugin indent on    " required
    " To ignore plugin indent changes, instead use:
    "filetype plugin on
    "
    " Brief help
    " :PluginList       - lists configured plugins
    " :PluginInstall    - installs plugins; append `!` to update or just :PluginUpdate
    " :PluginSearch foo - searches for foo; append `!` to refresh local cache
    " :PluginClean      - confirms removal of unused plugins; append `!` to auto-approve removal
    "
    " see :h vundle for more details or wiki for FAQ
    " Put your non-Plugin stuff after this line
    :set number

It's hard to see my code with color highlights. I want to keep the syntax color, but without the highlighting. I couldn't find the setting in ~/.vimrc. How do I disable this ?

PS : These highlights are not results of searching.

Answer 1

As noted by @Christian Brabbandt in the comment before, apparently, this is from YouCompleteMe auto-completion. As mentioned in YouCompleteMe, github about Diagnostic UI,

This turns on YCM's diagnostic display features including like the gutter signs, text highlighting, diagnostic echo and auto location list population. To disable this, I put :

let g:ycm_show_diagnostics_ui = 1

and the highlights are now gone.

Answer 2

it should be

let g:ycm_show_diagnostics_ui = 0