Upgrades from Dynamics NAV 2013 forward
With the release of Dynamics NAV 2015, Microsoft introduced the PowerShell upgrade that automates the code merging as well as the data upgrade. In order to take advantage of the PowerShell upgrade process, you need to be at least on Dynamics NAV 2013.
There are some limitations to the automated upgrade. This is listed on MSDN at https://msdn.microsoft.com/en-us/library/mt600251(v=nav.90).aspx.
Basically, what it says is the following:
If the names of your old variables are used in the newer version as a function or statement, you must change them before you upgrade
If your old code calls functions that do not exist anymore in the newer version, you must verify that the upgrade codeunits migrate data correctly
If the code you're coming from causes some fields on the table to be dropped, you'll need to make sure that it doesn't
If your company name uses special reserved characters in NAV, such as [ ~ @ # $ % & * ( ) . ! % - + / = ? ], then rename the company...
