compilation error on upgrading the project to 6.10.7 from 5.19

hi, 

i am getting this java compilation error on upgrading my project locally from 5.19 to 6.10.7. 

How do i resolve this ?

i did re-imported the community commons module again 

[javac] Compiling 477 source files to C:\Users\rachana.bp\Documents\Mendix\Marine-main\deployment\run\bin
    [javac] C:\Users\rachana.bp\Documents\Mendix\ Marine-main\javasource\communitycommons\Misc.java:660: error: unreported exception COSVisitorException; must be caught or declared to be thrown
    [javac]         overlay.overlay(new HashMap<Integer, String>()).save(baos);
    [javac]                                                             ^
    [javac] Note: Some input files use or override a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Note: C:\Users\rachana.bp\Documents\Mendix\ Marine-main\javasource\com\mendix\core\Core.java uses unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
    [javac] 1 error