Troubleshooting AEM 6.1 to AEM 6.2 Upgraded

When we try to upgrade website developed on AEM 6.1 to AEM 6.2 we need to consider below points.

Update uber.jar version to 6.2.0

<dependency>

    <groupId>com.adobe.aem</groupId>

    <artifactId>uber-jar</artifactId>

    <version>6.2.0</version>

    <scope>provided</scope>

    <classifier>obfuscated-apis</classifier>

</dependency>

Issue 1:
When tried to build code we normally see below error message.
java.lang.NoClassDefFoundError: com/day/cq/commons/Externalizer

06.07.2017 09:55:54.242 *ERROR* [0:0:0:0:0:0:0:1 [1499331350444] GET /content/kishore/en/test.html HTTP/1.1] 

com.day.cq.wcm.core.impl.WCMDebugFilter Exception: com/day/cq/commons/Externalizer

java.lang.NoClassDefFoundError: com/day/cq/commons/Externalizer

Solution:
Fixed this issue by rebuilding the package with AEM 6.2 uber.jar

Issue 2:
Caused by: org.apache.sling.scripting.sightly.SightlyException: Cannot find a a file corresponding to class com.aem.kishore.HelloWorld in the repository.

Solution:
This issue is caused due to the Java version. Use the correct java version preferably Java 8.