sshfs is failing with "remote host has disconnected"

Question

I'm running sshfs with the following:

sshfs basicuser@192.168.1.111:/var/www/myapp /home/basicuser/code -o sftp_server="/usr/bin/sudo /usr/libexec/openssh/sftp-server"

I have also created RSA keys so I can log in via ssh without password prompt (I tested this and it works).

I have also added the user to the sudoers file to run the sftp-server without a password:

basicuser  ALL=(ALL)  NOPASSWD:  /usr/libexec/openssh/sftp-server

What could be causing this error? How do I figure that out?

Edit

I am trying to mount a folder on the local computer from the remote server. On the remote server, only root has read/write permissions to that folder.

Remote folder: /var/www/myapp (is root only read/write)

Answer 1

It was requiring tty (this basically means something cannot be run in the background, but needs an active terminal window to run). So I added the following to /etc/sudoers (edited by doing visudo):

Defaults:basicuser !requiretty

I want it to not require tty only for that one command, but it may not be possible to do that: https://unix.stackexchange.com/a/80159

Answer 2

You get a lot more information about the failure if you run sshfs as:

sshfs -odebug,sshfs_debug,loglevel=debug user@host ...

Usually this will give you something a lot more helpful to debug the problem.

Answer 3

Thanks, @Alex Hofsteede for the debugging info.
my problem was that I was using a custom cipher, the Blowfish cipher.
command-line line 0: Bad SSH2 cipher spec 'blowfish-cbc'.
I removed the custom cipher and it worked.