Migration from APEX 4.X to Latest: Some Findings

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Scenario

The APEX.4.0 needed to be migrated to version 19.X. In this context the approach, best practices and any trouble shooters are explored. thanks to fac586 and Hoek who provided wonderful inputs through discussions in MOSC. For the benefit of others the findings are converted to a document.

Approach (Thanks to fac586)

Suggest  you read through the release notes for versions 4.0 to 18.x in the documentation archive to see what has changed, and use your knowledge of your application(s) to identify what is likely to have an impact.