./mvnw spring-boot:run command displays "Spring was unexpected this time" message

Spring Boot guide presents a demo example where to run the application ./mvnw spring-boot:run command inside the 'complete' folder/directory is used, in the case we are using the build framework maven. I tried this command from my windows power shell as well as command prompt but it displays the message "Spring was unexpected this time."

E:
├───src
    ├───main
    │   ├───java
    │   │   └───com
    │   │       └───example
    │   │           └───demo
    │   └───resources
    └───test
        └───java
            └───com
                └───example
                    └───demo

I am using Windows 7. The command prompt contents are as follows:

Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
    
E:\MyLearnings(Tech Front)\Spring Boot Learning\gs-spring-boot-master\gs-spring-boot-master\complete>mvnw spring-boot:run
\Spring was unexpected at this time.
    
E:\MyLearnings(Tech Front)\Spring Boot Learning\gs-spring-boot-master\gs-spring-boot-master\complete>./mvnw spring-boot:run
'.' is not recognized as an internal or external command, operable program or batch file.
    
E:\MyLearnings(Tech Front)\Spring Boot Learning\gs-spring-boot-master\gs-spring-boot-master\complete>.\mvnw spring-boot:run
\Spring was unexpected at this time.
    
E:\MyLearnings(Tech Front)\Spring Boot Learning\gs-spring-boot-master\gs-spring-boot-master\complete>