Vim E194: No alternate file name to substitute for '#'

Question

I am using ctrlp.vim plugin which is essentially a file finder. I followed the installation steps as mentioned here:

http://kien.github.io/ctrlp.vim/#installation (using git)

My plugin is working fine and as expected but on starting vim I get following error:

Error detected while processing FuncUndefined Auto commands for "*":
E194: No alternate file name to substitute for '#': runtime autoload/ctrlp#utils#cachedir.vim
Press ENTER or type command to continue

On removing set runtimepath^=~/.vim/bundle/ctrlp.vim from my vimrc the error goes away but obviously even my plugin stops working which is not desired.

Please help.

Answer 1

The format of that command is wrong: Instead of

runtime autoload/ctrlp#utils#cachedir.vim

it should be

runtime autoload/ctrlp/utils/cachedir.vim

The # separator is used when calling autoload functions, but :runtime requires a path, with path separators. In there, the special identifiers such as # and % are in effect, and that causes the error.

---

To fix that, find out from where this wrong command is issued.

:verbose autocmd FuncUndefined

is a good start.

Answer 2

I had the same error with the Windows version of GVim 8.1 when trying to write a [No Name] buffer to a file name containing #include. Placing a \ before each # in the filename works around the problem.

I thought it would conflict with the Windows convention of using backslashes to separate folders in file paths, but it didn't.