Error report:
(the figure above shows the error report when the server code is running in the virtual machine)

Memory error: it involves reading, saving and writing. The memory is not enough

Solution:
check and install 64 bit python. The pandas and numpy in 64 bit Python are 64 bit, and the memory is larger.

If running in a virtual machine: set the memory size of the virtual machine (this method I use)

run again, and no more errors will be reported: