Unhelpful HTTP api response from rails - ruby-on-rails

Question

I have an IOS app and I am passing an image with a couple strings to a rails API. I have started getting this error back from the rails. I couldn't find any info on what would be causing this error. I am assuming that it has something to do with passing a larger than average data package (an image)
.
{ status code: 500, headers {
Connection = close;
Date = "Fri, 15 Jul 2016 20:30:01 GMT";
Server = "nginx/1.4.6 (Ubuntu)";
"Transfer-Encoding" = Identity;
}
Should I be trying to solve this problem from a Client (IOS) or Server (Rails/nginx) perspective?
Potentially Helpful Info:
The rails controller api starts with
def image_build
begin
puts "Begin"
But "Begin" is never printed.
EDIT 1
Some more info:
in the IOS these lines have the output below:
print(response)
print(response.description)
print(response.data)
print(response.request)
print(response.response)
output:
SUCCESS:
SUCCESS:
Optional(<>)
Optional(<NSMutableURLRequest: 0x7fa9539506a0> { URL: http://www.example.com/api/image_build })
Optional(<NSHTTPURLResponse: 0x7fa9515c9cd0> { URL: http://www.example.com/api/image_build } { status code: 500, headers {
Connection = close;
Date = "Fri, 15 Jul 2016 20:30:01 GMT";
Server = "nginx/1.4.6 (Ubuntu)";
"Transfer-Encoding" = Identity;
} })
EDIT 2
I believe it is just timing out in a sense. When I remove the rails image upload and just have the IOS send the image over it still doesnt work. But if I tell the IOS to not send the image, the strings pass over successfully. So it only fails when the IOS tries to send the image.

Answer 1

I am not sure you would get the "puts" response, ideally you should use log statements like logger.debug or logger.info and check the log. Depending on which Rails env you are in, if in production it would be log/production.log or log/development.log in development env. It will give you more answers about why you are getting a 500 error.