Thanks, @p.belardi
I believe your problem is due to an issue which has been reported (DHIS2-15011) and fixed. The 2.39.2 release will hence include the fix and should be released within the next couple of weeks.
If you need to address the issue more urgently, there is a work around that involves adding some additional metadata into your system. See this post for example: Data entry app not loading - #21 by jaime.bosque