Error displaying plugin-in-all-txt in admin panel

hi all

i have been using grav for the past several years, but... now this problem popped up (i dont know what i did or if i mistakenly clicked something.).
with a fresh install everything goes fine.
but when i swap the new user folder with the user backup folder, the error (display plugin-in-all-txt. as shown in picture) returns.
i guess the problem is somewhere in the config or data folder, i guess. im lost.
help?
tnx in advance : )

double thank you @Karmalakas, that fix the issue > re-enabling translations in Admin

(i did try search, but i didnt knew how to address the issue, so i may have not used the right words for it.)