AWS S3 Errors - EntityTooSmall

I was recently reworking an upload process at my job to make use of the Multipart Upload service that is a part of AWS S3. Everything was working fine and I was able to send the 1 MB chunks off to S3. However, once I went to complete the multipart upload I started to receive the EntityTooSmall error back from the Ruby SDK. I wasn't entirely too clear about why it would complain since it accepted all of the chunks and only rejected things once I tried to complete the multipart upload.

The AWS docs do not do much to tell you what the hell happened if you are receiving this error. You will have to dig down to these docs to finally get some clue. Apparently AWS considers 5 MB to be the minimum size of a multipart upload that they should have to encounter (excluding the last chunk).