Error upgrading vaadin 7.2.6 to vaadin 8.3.0 with ant compile

i change the lib at vaadin 7.2.6 by the lib of vaadin 8.3.0 but when i compile with ant i got these errors

 C:\Consisint\Acsele\Acsel-e\Application\Core\EJBAcsel-e\src\com\consisint\acsele\reinsurance\advance\service\impl\ cannot access com.vaadin.server.VaadinServletService
 bad class file: com\vaadin\server\VaadinServletService.class(com\vaadin\server:VaadinServletService.class)
 class file has wrong version 52.0, should be 50.0
 Please remove or make sure it appears in the correct subdirectory of the classpath.
 import com.vaadin.server.VaadinServletService;

i don’t know why this happends

because you targeting wrong java version

trying to use jars which are compiled for 1.8 with older compiler. use newer sdk in your project. this should solve the problem.

the system works with java 1.6 and in the company they want to change to vaadin 8.3.0

I have to find jar of vaadin 8.3.0 that work with java 1.6 … is it possible?

they using functional interfaces. so i guess not. you can give a shot take vaadin version 7.

the system using vaadin 7.2.6 but the company wants update to vaadin 8.3.0… but without changing the java version yet…thats possible?

You need Java 8 in order to use Vaadin 8+. For reference here are the corresponding version numbers for Java:

  • Java 6 uses major version 50
  • Java 7 uses major version 51
  • Java 8 uses major version 52
  • Java 9 uses major version 53

yes … the decision in the company was to change to java 8.