I don't see an easy solution. Maybe someone else recognizes it.
What I would do in your place:
1) disable non-Prestashop modules. You can either rename or remove the subdirectories ofto Modules or use Prestools to change the Prestashop flag.
2) remove all overrides. Same solution options.
3) replace all directories except for /app, /config, /img, /mails, /pdf and /themes with the files from a fresh PS installation of the same version. Sometimes a file hasn't been copied well and that causes problems. This can solve that kind of problem. (rename the old directories as a kind of backup).
These are very generic solutions. But it is all I have to offer.