S3 giving me NoSuchKey error even when the key exists

A generic answer that may useful to those who are thinking about file paths and may be new to the AWS S3 terminology. Not getting the "name" and "key" right will often lead to an exception with the message An error occurred (NoSuchKey)... as posted in this question.

Let's say that you have a JPEG file stored in some "path" in a bucket. Navigating to this object on the AWS console shows the S3 URI to be:

s3://my-bucket/some/very/long/path/my-image.jpeg

You could read the my-image.jpeg object in Python with this basic example:

import boto3

s3client = boto3.client('s3', region_name='us-east-1')

bucket_name = 'my-bucket'
object_key = 'some/very/long/path/my-image.jpeg'

try:
    s3obj = s3client.get_object(Bucket=bucket_name, Key=object_key)
except Exception as e:
    print(f"Error reading key {object_key} from bucket {bucket_name}: {e}")
else:
   print(f"Got object: {s3obj}")

You have a %0A at the end of your URL; that's a line separator.

Since you know the key that you have is definitely in the name of the file you are looking for, I recommend using a filter to get objects with names with your key as their prefix.

s3 = boto3.resource('s3')
bucket = s3.Bucket('cypher-secondarybucket')
for obj in bucket.objects.filter(Prefix='MzA1MjY1NzkzX2QudHh0'):
    print obj.key

When you run this code, you will get the key names of all the files that start with your key. This will help you find out what your file is exactly called on S3.