After upgrading YouCompleteMe recently, it stopped working. My first thought was that the libraries needed rebuilding:

python install.py --gocode-completer --clang-completer

The rebuild finished successfully, but each time I started vim I saw a message that the YCM server had crashed. I tried enabling logging with the following commands, but that didn’t work (it was crashing before anything could be logged)

let g:ycm_server_log_level = 'debug'
let g:ycm_server_keep_logfiles = 1
let g:ycm_server_use_vim_stdout = 0

It turns out that the issue was my use of python rather than python2 when building YouCompleteMe. To fix the issue, rebuild the library using python2 rather than python python2 install.py –gocode-completer –clang-completer Once this is done, I added let g:ycm_path_to_python_interpreter = '/usr/bin/python2' to my .vimrc everything seems to be working great again.

If you get an error about libtinfo, you may need to install ncurses5-compat-libs via the AUR