Empty sub-directories check and if no searching files inside checking

I have few main-directories with many subdirectories, I have to campare some information from my sub-s but only -vol with text file(I'm ok over here), my tree it looks like:

dir1-sub1
    -...
    -vol1
    -vol2
    -vol3
dir2-sub1
    -...
    -vol1
    -vol2
    -vol3
etc...

I want to use only vol2 everytime , im ok with that, I use inside -in os.walk and .startswitch() method - to get only vol2,

My problem is when some times vol2 is empty and I'cant do my action , have an error. That's a part of my script, I've tried it with try but not works and I'm blocked with that:

for dirname in os.listdir(path):
#print(dirname, "dirname")
#new_dirname = "#" + dirname
#print(new_dirname)
if dirname in open("F:\exif_time_packages_gopro\\BR.txt").read():
    #print(dirname, " in list")
    new_dirname = path + "\\" + dirname
    print(new_dirname, "new")

    for dir in os.listdir(new_dirname):
        if dir.startswith('vol2'):
            new_dir = new_dirname + "\\" + dir
            print(new_dir)# I have all my vol2 over here <<<
            empty = False
            try:
                if os.stat(new_dir).st_size > 0:
                    print("not empty",dir)
                else:
                    print("empty sub")
            except:
                pass

My question is how can I switch a subdir when he is empty to vol1 and do my action in my loop, on this subdir vol1, how to use exception. Second question and problem is when I open vol2, I'm looking inside for file with name is "gpr" and sometimes ther are missing, how to write it when gpr, is missing pass to next dir. So I would like to check:

-if is empty(switch to vol1) and if have no gpr(pass)

-if not empty and gpr inside(do my action)

I don't know how to overwrite it, I've tried already few solution from here all day yesterday and nothing works.

Any help will be appreciated