I needed to send an URI through [Nginx](http://wiki.codemongers.com/Main) to the backend servers ([Mongrel](http://mongrel.rubyforge.org/)) intact. However Nginx was constantly unescaping the URI, and removed slashes in the process. That resulted in an invalid URL at the backend server. The fix was **simple**, but extremely hard to find. Just remove the trailing slash from the *proxy\_pass* directive, like below.
Invalid URI is sent to the backend server with this configuration of Nginx.
```bash
proxy_pass http://backend1:3000/;
```
Valid, untampered URI is sent with this configuration of Nginx.
```bash
proxy_pass http://backend1:3000;
```