We were using ADempiere 3.9.0 with some customised columns in the production.
As part of upgrade to 3.9.3, We have followed the steps mentioned in the http://wiki.adempiere.io/Migrate. We have used Migration Tool.
From the reading what I understood is
The process took 4.5 hours to completed in my 8GB RAM PC and generated 9792 errors and 1851 warnings.
While trying logging to the migrated production database to see the complete errors, we identified that certain columns we created in AD_Role is removed from that table(But AD_Column of the same table still exists).
The 'Migration' window is not recorded any errors.
The below is my doubts:
On the other hand, for custom fields, they must be identified with their own entity or the customization entity so that the migration tool does not delete them, if your new fields in the window have the Dictionary entity, they will be overwritten or not migrated.
In other words, the migration tool is based on any definition in the application dictionary and only migrates those that are correctly identified.
On the other hand, if you have modified any component of the application dictionary, this change generates a history which should be marked as customization, since the tool at the end of the migration takes all the historical changes and applies those that were marked as customization