Change update file configuration.

With Spring Boot 2.x , the servlet update file configuration has changed.

Change the configuration

spring.http.multipart.max-file-size=1024KB
spring.http.multipart.max-request-size=1024KB

to

spring.servlet.multipart.max-file-size=1024KB
spring.servlet.multipart.max-request-size=1024KB

See #4.