Just tried accessing my localhost today, but it doesn't work. I worked yesterday, but I believe it's because my Mac crashed. I've tried started httpd again with brew services start httpd. This results in:

Bootstrap failed: 5: Input/output error
Try re-running the command as root for richer errors.
Error: Failure while executing; `/bin/launchctl bootstrap gui/501 /Users/UserName/Library/LaunchAgents/homebrew.mxcl.httpd.plist` exited with 5.

Have tried reinstalling httpd, but it still gives the same error.
Any ideas what the cause can be?