Cannot create hdf5 file with h5py.file() - hdf5

Question

I'm trying to write my results in two separate hdf5 files. My code works for one of them but produces an error for the other one, even though the code for both is identical. Here is my code:
def test(model, outfile_f3,outfile_f5):
dtype = torch.FloatTensor
path = args.imagefolder
filenames = sorted(glob.glob(os.path.join(path, '*.png')))
N = len(filenames)
f3_activations = []
f5_activations = []
for i in range(N):
fname = filenames[i]
print(fname)
v = Image.open(fname)
image = load_image(v, image_sizes['eig'])
image = torch.from_numpy(image).type(dtype).cuda()
image = image.unsqueeze(0)
att, f3, f5, latent = model(image, segment=args.segment, add_offset=args.addoffset and args.segment, test=True)
#latents.append(latent.detach()[0].cpu().numpy().flatten())
#attended.append(att.detach()[0].cpu().numpy().flatten())
f3_activations.append(f3.detach()[0].cpu().numpy().flatten())
f5_activations.append(f5.detach()[0].cpu().numpy().flatten())
file_f3 = h5py.File(outfile_f3, 'w')
file_f3.create_dataset('f3_activations', data=np.array(f3_activations))
file_f3.close()
file_f5 = h5py.File(outfile_f5, 'w')
file_f5.create_dataset('f5_activations', data=np.array(f5_activations))
file_f5.close()
#asciiList = [n.split('/')[-1][:-4].encode("ascii", "ignore") for n in filenames]
#f.create_dataset('filenames', (len(asciiList), 1), 'S10', data=asciiList)
outfile_f3 and outfile_f5 have previously been defined as:
outfile_f3 = os.path.join('./output', 'f3_activations.hdf5')
outfile_f5 = os.path.join('.output','f5_activations.hdf5')
When I try to run the script that uses test function I get the following error:
File "record_f3_and_f5_actvations.py", line 109, in test
file_f5 = h5py.File(outfile_f5, 'w')
File "/gpfs/milgram/project/yildirim/ms3542/conda_envs/env/lib/python3.6/site-packages/h5py/_hl/files.py", line 408, in init
swmr=swmr)
File "/gpfs/milgram/project/yildirim/ms3542/conda_envs/env/lib/python3.6/site-packages/h5py/_hl/files.py", line 179, in make_fid
fid = h5f.create(name, h5f.ACC_TRUNC, fapl=fapl, fcpl=fcpl)
File "h5py/_objects.pyx", line 54, in h5py._objects.with_phil.wrapper
File "h5py/_objects.pyx", line 55, in h5py._objects.with_phil.wrapper
File "h5py/h5f.pyx", line 108, in h5py.h5f.create
OSError: Unable to create file (unable to open file: name = '.output/f5_activations.hdf5', errno = 2, error message = 'No such file or directory', flags = 13, o_flags = 242)
It has no problem with creating, opening and writing in the file f3_activations.hdf5, but for some reason, it can't do the same with f5_activations.hdf5