GoogleAppEngine error directory not found
Your full project path contains two space characters and needs to be quoted, also, a trailing slash might be required i.e.:
C:\Python27\python.exe appcfg.py update "C:\Users\alastair\Desktop\School Files\Proxy Files\mirrorrr-master\mirrorrr-master\" assuming that's where you have your app.yaml file.
In your case it's thinking you are pointing to "C:\Users\alastair\Desktop\School" file which does not exist and thus showing the error.
Ive been working on get a proxy working for when im school, to access sites that i use alot for work but my school dont like.. This is the error it comes up with when i try to upload the files to googles app engine..

C:\Program Files (x86)\Google\google_appengine>"C:\Python27\python.exe" appcfg.p
y update C:\Users\alastair\Desktop\School Files\Proxy Files\mirrorrr-master\mirrorrr-master
09:44 PM Host: appengine.google.com
Usage: appcfg.py [options] update  | [file, ...]
appcfg.py: error: Directory does not contain an School.yaml configuration file

So im very confused on why it is asking for a "School.yaml" But i made one anyway, And even though its been made, it still displays this error, So if anyone can help, Please!