Type Error: unsupported operand type(s) for +: 'int' and 'str'

Metaphlan 4.1.1
db vJun23

While running the program for 104 samples this error occured during processign of my 45th sample:

Traceback (most recent call last):
File “/home/alex/miniconda3/envs/metaphlan4/bin/metaphlan”, line 10, in
sys.exit(main())
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 1555, in main
cl2ab, _, tot_nreads = tree.relative_abundances(
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 939, in relative_abundances
tot_ab += clade.compute_abundance()
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in compute_abundance
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 710, in
sum_ab = sum([c.compute_abundance() for c in self.children.values()])
File “/home/alex/miniconda3/envs/metaphlan4/lib/python3.9/site-packages/metaphlan/metaphlan.py”, line 758, in compute_abundance
rat, nrawreads, loc_ab = float(sum(rat_v)) or -1.0, sum(nreads_v), 0.0
TypeError: unsupported operand type(s) for +: ‘int’ and ‘str’

…afterwards it resumed processing of next samples. Most of my samples have no detectable microbial taxa, therefore I do not see a difference between the resulting profile and the rest of the samples.

Could this be a problem with my .fa file?
thanks a lot for the nice package and your time