Marafa

Walk through your registration process?  What do you ask from your user?  Do you ask them to complete a profile after registration?  That’s the info you collect. 
And how is it deleted?  IPB does not delete info automatically. That’s done by you. What’s YOUR policy if someone wants to remove their account?  Do you allow accounts to be deleted?  Do you anonymize posts made or delete them if the account is removed?  

These questions are about your site’s policy and procedures. It can’t be dictated by software. If you don’t have these policies documented, this would be a good time to do so.  

You will want to go to the System Log and review the log entry mentioned there. You will want to test the URL which it was encountered on and see if the error still exists. If it doesn't, this likely was resolved by upgrading the core or third party application/plugin, an issue you resolved in your custom theme, etc... If it still exists, you will want to check the aforementioned items for upgrades, if they are available, you will want to upgrade. If that doesn't resolve your problem, you will want to disable third party applications/plugins and switch to an unmodified theme. If that still doesn't resolve the problem, please let us know.

You can use this to create a request for support:
 
 

The column that stores the best answer post ID on IPS 4.4 is the same from IP.Board 3.4. I don’t believe they will change that. 
Anyway. I’ll take a look and reply back when Beta1 is out.

Thanks for the heads up, Adriano.
What really would be helpful would be a migration step or tool from your Plugin to the feature. 
I'd lose a couple of years with marked answers...
 

Thanks , will try it
I really do not know what this is not available as a core feature
The assumption that the suitable user interface language  is always the windows language is not valid for a considerable number of users  in  several non English speaking countries
 

You could use our plugin