I tried to restart apache2 and it failed. I got the message below. It was working before so I don't know what went wrong and how to fix it. I'm on Ubuntu 16.04 on windows 10.
* Restarting web server apache2 [fail]
* The apache2 configtest failed.
Output of config test was:
apache2: Could not open configuration file /etc/apache2/apache2.conf: Input/output error*
Action 'configtest' failed.
cpfrom/mnt/c/…, put your config back in place. But I'm not sure, haven't actually used Ubuntu on Windows)