pysftp - IOError - No such file when I can see the full file on the other end

Question

I have a program which transfers files to different endpoints. Only one endpoint in particular fails on this conn.put():

try:
  conn.put(fileToPush, pushedFile)
except IOError as ioe:
    self.logPush('IOError: {} - Exiting...'.format(str(ioe)))

The output:

IOError: [Errno 2] No such file - Exiting...

But I sftp to the destination from the command line and I do an "ls -ltr" and one of the two files I'm trying to push is there.

The file's size is 900117 bytes. Then on sftp, I can also see the file size as 900117 bytes.

How does it transfer 1 whole file and still run into an IOError?