I just updated a number of sites from MODX version 2.7.0 (and 2.6.5) to version 2.7.1
I encountered the following errors:
upgrading from 2.7.0
Error updating table for class modResource Array (  => 42S21  => 1060  => Duplicate column name 'alias_visible' )
upgrading from 2.6.5 (and on one site from 2.7.0)
Error updating table for class modResource Array (  => HY000  => 1283  => Column 'description' cannot be part of FULLTEXT index )
all the sites seem to work fine notwithstanding the errors on upgrade . . .