I have a very basic app.yaml file. When I deploy the file with this in it:
basic_scaling:
#max_instances: 11
#idle_timeout: 10m
#instance_class: B1
everything works. If I un-comment out instance_class: B1 I get the error "class B1 only available for basic_scaling" which it already is so why the error. The other thing is if I leave everything the way it is but un-comment out the max_instances then everything uploads but when I go to the project I get a 500 error. Changing the scaling to automatic and leaving the max_instances uncommented out does not cause errors.
strange behavior!