Can't access 'modules' tab after upgrade to 1.5.1.3

Hello,

I'm getting a (blank) screen when I try to get into my 'modules' page after I upgraded my opencart version to 1.5.1.3. The upgrade was successful and everything is working the way it should, but I can't access my modules.

I tried emptying the cache and (I think) I did some hard refreshes but it doesn't seem to work.

Does anyone know if there's a quick fix for this?

I'm getting this identical error and tried like five times to perform the upgrade from 1.5.1.2 to 1.5.1.3:
Then, since i have spanish language in my OC i tried and duplicated the "english" folders in ADMIN and CATALOG and renamed as "spanish" so now i have both "english" and "spanish" folders. The error i get is somewhat different:
What the problem could be???

in the upload/install/controller folder in the patch I downloaded from Q's link on this forum there are definitely files missing in that folder, probably:
footer.php and header.php I think
I had this error on me local dev platform

I'll check the files again.. I use winmerge like I always do to compare and export the list of changes so there should be no mistake

There are, indeed, no files missing in the specified folder (as you said). Any idea though why this error message comes up?

Small update.. oh god I feel stupid. Does anyone know how this 'problem' can be resolved?

How did you manage to solve the error message you initially reported in your first post??