I currently only own the DE eCart 5 and a few alacart extensions (do not have the fund to upgrade to the integrated data bridge package yet)
So I usually install DE ala cart extentions (UE4, Datassist 2, Cookie Toolkit 3, sometimes Security assist 1 but have not installed it yet so not a factor in the error ) then do eCart 5. so your saying i should do Ecart first then DE then the other 4?