Hello,
I got above mentioned error while installing discourse on aws ec2. The problem was with my SES smtp password ( AmQ/22sNDN2Bg5vS+zH3IDfy+lfmF3OgGg/CnsAZMg90 ). Later I changed the password to one without any special characters and it worked. I am not sure its a bug or discourse wont encourage password with special characters. I thought I have to inform.
Regards
Did you put quotes around your password when editing the app.yml file?
@zogstrip No, I didn’t put any quotes around the password.I simply copied and pasted the password into the app.yml. Actually this is not the first time I am installing discourse. This error happens to me today, when I am trying to have a fresh discourse install.
And that’s probably the cause.If you have some special characters, you should encase it in the quotes, so that Discourse knows where it begins and ends.
It’s a bug/limitation in ./discourse-setup. It doesn’t properly escape passwords before asking sed to do the replacement.
One solution would be to check the password for a set of delimiters before doing the replacement and then choose the replacement delimiter accordingly.
Another would be to check for a slash in the password and punt, then tell them to change the password or edit app.yml by hand.
I’ll add this to my TODO list of improvements to discourse-setup.
Oh. I was wrong.
I’ll add putting quotes around the password in samples/standalone.yml to my list as well. 
I’ve got a couple other yml updates I have been wanting to do as well.
Whatever is easiest to do, is best here…