strange migration errors - Joomla! Forum - community, help and support

i trying migrate latest 2.5x 3x
i followed guides namely leos , have backup great akeeba.
so have 3rd -4th attempt , each time finalize url blank.

and there no behind scenes errors (have them turned on , asked host)

from administrator index.php can show run app->execute nothing gets rendered , no errors.
what checks can see if db ran ok or go here. php errors not here.

here url left -

administrator/index.php?option=com_joomlaupdate&task=update.finalise

any ideas moving forwards. take database , match fresh 3x install ? how can check if files 3x etc..

thank advice.

from understanding

require_once jpath_base . '/includes/defines.php';

if rename file there should error require must able load file. not error here. right ? there kind of caching load file cached version if renamed it.