How to make sure code is uptodate

I am running suitecrm from the early days of suitecrm, migrated from sugar, which I was using since version 5.2 and upgraded over time, i would not say regularly but quite often.
While we were running sugar 5.x we migrated from linux/mysql to iis /MSSQL, the reason was that we wanted to have more interoperability with our GreatPlains ERP system.

Regarding operations most operations runs fine but I have some errors that are logged and I can not find solution (I find similar error on the forum with no solution).

*** over time it happened that while I was performing an update, the update process ended in a white page, when this happened I was restarting the update and the process completed with the assumption that it was ok…

I suspect that my code is not uptodate and that I have mismatched file version.

my intention is to update to 7.5, and overwrite the module directory from a fresh 7.5 install and perform a quick repair. My customisation are in custom direcotry so I am ok regarding code.

Would that work or you have another suggestion?

thank you